Rare earth permanent magnet powder, method for producing same and bonded magnet

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rare earth permanent magnet powder which exhibits superior magnetic properties, particularly anisotropy and corrosion resistance, a method for producing the same, and bonded magnets produced using the above rare earth permanent magnet powder.
2. Prior Art
The rare earth-iron-boron alloy permanent magnet powder, comprising iron (Fe), boron (B) and a rare earth element (which is now defined to include yttrium (Y) and will be hereinafter represented by R when appropriate), has drawn general attention as a permanent magnet material which exhibits superior magnetic properties, and it has since been in the development stage as a magnet powder for bonded magnets. Although a bonded magnet is inferior in magnetic property widen compared to sintered magnets of the same magnet powder. Its field of application has grown and continues to grow rapidly in recent years because of its superior physical strength and higher flexibility in shape. These bonded magnets are composed by binding magnet powder with organic binders and/or metallic binders, or the like; and magnetic properties of these bonded magnets depend on the magnetic properties of such magnet powders.
Japanese Patent Application A-Publication No. 1-132106 describes one prior art R-Fe-B permanent magnet powder used to manufacture a bonded magnet. The R--Fe--B permanent magnet powder is manufactured by preparing a R--Fe--B alloy having a ferromagnetic R.sub.2 Fe.sub.14 B intermetallic compound phase as its principal phase, subsequently heat-treating the alloy in a prescribed temperature range in a hydrogen atmosphere to cause phase transformation in RH.sub.x phase, Fe.sub.2 B phase and the remaining Fe phase, and subsequently subjecting the alloy to dehydrogenation to reproduce the R.sub.2 Fe.sub.14 B phase. The resulting magnet powder has an aggregated structure of recrystallized grains of R.sub.2 Fe.sub.14 B phase having a minuscule average grain size of 0.05 .mu.m to 3 .mu.m.
Japanese Patent Application A-Publication No. 1-132106 further describes a R--Fe--Co--B permanent magnet powder, i.e., a R--Fe--B magnet powder in which a part of Fe is substituted by cobalt (Co). This magnet powder has also an aggregated structure of recrystallized grains of R.sub.2 (Fe,Co).sub.14 B phase having an average grain size of 0.05 .mu.m to 3 .mu.m.
The aforesaid prior art magnet powders exhibit magnetic anisotropy, but anisotropy is often reduced due to small fluctuations in alloy composition or manufacturing conditions, and hence it is difficult to obtain stable and superior magnetic anisotropy.
Known methods for imparting magnetic anisotropy to a magnet powder involve subjecting the permanent magnet powder to hot plastic working, such as hot rolling and hot extrusion, to thereby form the crystal grains of the magnet powder into a flat shape. In such a hot plastic working, however, the degree of working varies depending upon the locations, and hence a magnet powder having a stable and uniform magnetic anisotropy cannot be obtained. In addition, the manufacturing process is intricate, and hence the manufacturing costs are unduly high.
Furthermore, the flat recrystallized grains formed by means of hot plastic working are more susceptible to corrosion than the magnet powder comprising recrystallized grains which are not hot-worked. As a result, when the magnet powder is kept in a high-temperature and high-humidity atmosphere, such as in a factory, for a prolonged period of time, the surface of the magnet powder is corroded, and its magnetic property is unduly reduced.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a rare earth permanent magnet powder which exhibits superior magnetic properties and high resistance to corrosion.
Another object of the invention is to provide an improved method which can produce the above permanent magnet powder without conducting any hot plastic working such as hot rolling.
Yet another object of the invention is to provide a bonded magnet produced using the above permanent magnet powder.
According to a first aspect of the invention, there is provided a rare earth permanent magnet powder comprising particles each containing 10 to 20 atomic percent of R, 3 to 20 atomic percent of B, 0.001 to 5.0 atomic percent of at least one element selected from the group consisting of Ga, Zr and Hf, balance Fe, or Fe and Co, and unavoidable impurities, the individual particle comprising an aggregated structure of recrystallized grains containing a R.sub.2 Fe.sub.14 B intermetallic compound phase as a principal phase, the intermetallic compound phase consisting of recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 to 20 .mu.m, wherein at least 50% by volume of the recrystallized grains of the aggregated structure includes recrystallized grains formed so that a ratio of the greatest dimension to the smallest dimension is less than 2 for each recrystallized grain. In the foregoing, the composition of the alloy may be modified to further improve the magnetic properties and high resistance to corrosion of the magnet powder.
According to a second aspect of the invention, there is provided a method for producing a rare earth permanent magnet powder comprising the steps of:
(a) preparing a rare earth alloy material and a regenerative material;
(b) subsequently elevating the temperature of the alloy material and the regenerative material in a hydrogen atmosphere and holding the same in the hydrogen atmosphere at a temperature of 750.degree. C. to 950.degree. C.;
(c) subsequently holding the alloy and the regenerative material at a temperature of 750.degree. C. to 950.degree. C. in a vacuum; and
(d) subsequently cooling and crushing the alloy.
According to a third aspect of the invention, there is provided a bonded magnet produced using the permanent magnet powder as described above.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a photomicrograph of a microstructure of a R--Fe--B permanent magnet powder in accordance with the present invention;
FIG. 2 is a photomicrograph similar to FIG. 1, but showing a microstructure of an R--Fe--Co--B permanent magnet powder in accordance with the present invention; and
FIGS. 3 and 4 are schematic, cross-sectional views, each showing the state in which R--Fe--B alloy ingots and regenerative materials are contained together in a vessel.

DESCRIPTION OF THE INVENTION
The inventors have made an extensive study in regard to the improvement of the prior art magnet powders, and have come to the understanding that among permanent magnet powders comprising a recrystallized grain structure of R.sub.2 Fe.sub.14 B principal phase, the magnet powder containing 0.001 to 5.0 atomic percent of at least one of gallium (Ga), zirconium (Zr) and hafnium (Hf), can be produced so as to have superior magnetic anisotropy without subjecting the powder to hot plastic working, in addition, the R--Fe--B permanent magnet powder comprising a structure of recrystallized grains for which (greatest dimension b)/(smallest dimension a)<2 for each recrystallized grain indicates substantially improved corrosion resistance.
The permanent magnet powder in accordance with the present invention is produced based on the aforesaid facts, and is characterized in that each particle contains 10 to 20 atomic percent of R; 3 to 20 atomic percent of B; 0.001 to 5.0 atomic percent at least one of Ga, Zr and Hf or further added 0.01 to 2.0 atomic percent of at least one of Al, V and Si; balance Fe; and unavoidable impurities; that an individual particle thereof comprises a structure of recrystallized grains containing a R.sub.2 Fe.sub.14 B intermetallic compound please as a principal phase, the intermetallic compound phase consisting of recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 to 20 .mu.m, and that the ratio or the greatest dimension b to the smallest dimension a is less than 2 for each recrystallized grain.
The permanent magnet powder as described above is produced as follows:
Prescribed materials are melted and cast into a R--Fe--B alloy material of a predetermined composition containing Ga, Zr or Hf, or further added Al, V and Si and the alloy material thus produced is heated in a hydrogen atmosphere and further subjected to heat treatment at 500.degree. C. to 1000.degree. C. either in a hydrogen gas atmosphere or in a mixed gas a atmosphere of hydrogen and inert gases. Thereafter, the alloy material is subjected to dehydrogenation at 500.degree. C. to 1000.degree. C. until the atmosphere reaches a vacuum having hydrogen gas pressure of no greater than 1 torr, or an inert gas atmosphere wherein the partial pressure of hydrogen gas is no greater than 1 torr. Then, the alloy is cooled, and the permanent magnet powder is thus produced.
In addition, if the R--Fe--B alloy is homogenized at a temperature of 600.degree. C. to 1200.degree. C., or if the dehydrogenated alloy is heat-treated at a temperature of 300.degree. C. to 1000.degree. C., the magnetic anisotropy and corrosion resistance are further improved.
The R--Fe--B permanent magnet powder thus produced comprises an aggregate structure of recrystallized grains of the R.sub.2 Fe.sub.14 B phase which contains neither impurities nor strain in the grains or at the grain boundaries. The recrystallized grain structure of each particle is formed so its to have an average grain size ranging from 0.05 .mu.m to 20 .mu.m. If it is less than 0.05 .mu.m, it is difficult to magnetize the powder. On the other hand, if it is greater than 20 .mu.m, the coercivity and squareness of the magnetization curve will be reduced, resulting in inferior magnetic properties. It is however more preferable that the average grain size ranges from 0.05 to 3 .mu.m, which is close to about 0.3 .mu.m, wherein the recrystallized grains become particles of a single magnetic domain. In addition, each recrystallized grain should preferably have such a shape that the ratio of the greatest dimension b to the smallest dimension is less than 2, and the amount of the recrystallized grains of such a shape should be at least 50% by volume of the total amount of recrystallized grains. Due to the recrystallized grains of the above shape, the coercivity and corrosion resistance of the R--Fe--B permanent magnet powder can be improved. When compared with the magnet powder produced by means of hot plastic working, the resulting magnet powder is superior in corrosion resistance and exhibits stable and excellent magnetic properties. In addition, the yield in manufacture is improved.
Moreover, the recrystallized grain structure of the R--Fe--B magnet powder thus obtained is an aggregated one that consists essentially of recrystallized grains of R.sub.2 Fe.sub.14 B phase and has almost no R-rich please on the grain boundary. Therefore, the value of the magnetization of the magnet powder can be further enhanced, and the corrosion which may develop through the R-rich phase on the grain boundary is prevented. In addition, there exist no strains due to hot plastic working, stress corrosion can be avoided. Thus, the corrosion resistance of the magnet powder is improved.
Furthermore, wheel boarded magnets are produced using the above permanent magnet powder, the resulting magnets also exhibit superior magnetic anisotropy and corrosion resistance.
The reasons for the limitation of the numerical range of the alloy composition are as follows:
(a) with respect to R
R represents at least one element selected from the group consisting of neodymium (Nd), praseodymium (Pr), terbium (Tb), dysprosium (Dy), lanthanum (La), cerium (Ce), holmium (Ho), erbium (Er), europium (Eu), samarium (Sm), gadolinium (Gd), thulium (Tm), ytterbium (Yb), lutetium (Lu) and Y. Nd is mainly used, and other rare earth elements are added to it. Among those elements, Tb, Dy and Pr enhance coercivity (iHc). If the R content is less than 10 atomic percent, the coercivity of the resulting permanent magnet powder becomes insufficient. On the other hand, if the R content exceeds 20 atomic percent, sufficient coercivity cannot be obtained. Therefore, the R content should be determined so as to be within the range of 10 atomic percent and 20 atomic percent.
(b) with respect to B
If the B content is less than 3 atomic percent or greater than 20 atomic percent, the coercivity of the permanent magnet powder is reduced, resulting in inferior magnetic properties. Therefore, the B content is determined to the range of between 3 to 20 atomic percent.
(c) with respect to Ga, Zr or Hf
Ga, Zr or Hf contained in the permanent magnet powder enhances coercivities and imparts superior magnetic anisotropy and corrosion resistance. If the content is less than 0.001 atomic percent, desired effects cannot be obtained. On the other hand, if the content exceeds 5.0 atomic percent, the magnetic properties are deteriorated. Therefore, the content of one or more of these elements is determined so as to range from 0.001 atomic percent to 5.0 atomic percent.
In the foregoing, 0.01 to 2.0 atomic percent of at least one of aluminum (Al), vanadium (V) and silicon (Si) may further be added in the R--Fe--B permanent magnet powder as necessary. Such an element enhances maximum energy product when its content is no less than 0.01 atomic percent. However, even if it is added in an amount of greater than 2.0 atomic percent, the magnetic properties cannot be improved, and hence the content should range from 0.01 atomic percent to 2.0 atomic percent.
The above reasons will be also applicable to the bonded magnets produced of the same R--Fe--B permanent magnet powder.
Furthermore, a part of Fe in the aforesaid R--Fe--B permanent magnet powders of various kinds may be substituted by Co. This modified permanent magnet powder is characterized in that it contains 10 to 20 atomic percent of R, 0.1 to 50 atomic percent of Co, 3 to 20 atomic percent of B, 0.001 to 5.0 atomic percent of at least one of Ga, Zr and Hf, balance Fe and unavoidable impurities, and that the individual particle thereof comprises a structure of recrystallized grains containing a R.sub.2 (Fe,Co).sub.14 B intermetallic compound phase as a principal phase, the intermetallic compound phase consisting of recrystallized grains of a tetragonal crystal structure having an average crystal grain size of 0.05 to 20 .mu.m, the ratio of the greatest dimension b to the smallest dimension a being less than 2 for each recrystallized grain.
Co existing in the permanent magnet powder enhances coercivities and magnetic temperature characteristics, e.g., Curie point, and further improves the corrosion resistance. However, if the Co content is less than 0.1 atomic percent, desired effects cannot be achieved. On the other hand, if the Co content exceeds 50 atomic percent, the magnetic properties are deteriorated instead. Therefore, the Co content is determined so as to range between 0.1 and 50 atomic percent. However, it is more preferable that the Co content ranges from 0.1 to 20 atomic percent since the coercivities reach the maximum within this range.
In the R--Fe--B alloy and R--Fe--Co--B alloy magnet powders as described above, Al, V or Si may be further added as is the case with the previous R--Fe--B alloy magnet powder.
The processes for manufacturing the above permanent magnet powders wall next be described.
After an extensive study, the inventors have clarified the causes of the variations in the manufacturing process. More specifically, in a hydrogen atmosphere at 750.degree. C. to 950.degree. C., the R.sub.2 Fe.sub.14 B phase of the R--Fe--B alloy ingot or powder is transformed into three phases as follows:
R.sub.2 Fe.sub.14 B.fwdarw.RH.sub.2 +Fe+Fe.sub.2 B (1)
Thereafter, in the dehydrogenation process, the phase is again transformed into an aggregated structure of recrystallized grains of R.sub.2 Fe.sub.14 B phase as follows:
RH.sub.2 +Fe+Fe.sub.2 B.fwdarw.R.sub.2 Fe.sub.14 B (2)
The reaction (2) is endothermic, and the temperature fluctuates while being lowered during the reaction. In addition, the temperature also varies depending upon location in the vessel into which the R--Fe--B alloy ingot or powder is filled. Due to these temperature variations, the magnetic anisotropy of the recrystallized grain structure of the resulted R--Fe--B permanent magnet powder is variable.
The inventors have determined that in order to effect the above reactions uniformly without causing any variability, the temperature elevation step, from room temperature to the temperature of 750.degree. C. to 950.degree. C., should be carried out in a hydrogen atmosphere, and have also found that the use of regenerative material is very effective. Namely, when the R--Fe--B alloy ingot or powder is heated to a prescribed temperature together with a regenerative material in a hydrogen atmosphere and is then kept in a vacuum at the same temperature, the temperature variation during the endothermic reaction (2) is prevented by the heat conserving effect of the regenerative material, so that the temperature is uniformly maintained at a prescribed high temperature. Therefore, the lowering and fluctuation of the magnetic anisotropy for the resulting R--Fe--B permanent magnet powder call be eliminated.
The inventors have also found that when a R--Fe--(Co)--B alloy ingot or powder containing 8 to 30 atomic percent of R; 3 to 15 atomic percent of B; 0.01 to 5.0 atomic percent of at least one of Al, Si and V; balance Fe or Fe and Co and unavoidable impurities, the powder becomes less sensitive to the temperature fluctuation during the dehydrogenation, so that the obtained magnet powder becomes excellent in magnetic properties, particularly in coercivity and squareness of the magnetization curve.
The method in accordance with the present invention is hence characterized by the steps of (a) preparing a rare earth alloy material and a regenerative material; (b) subsequently carrying out the temperature elevation step in a hydrogen atmosphere and holding the alloy material and the regenerative material together in the same atmosphere at a temperature of 750.degree. C. to 950.degree. C.; (c) subsequently holding them at the same temperature in a vacuum; and (d) subsequently cooling and crushing the alloy.
In the foregoing, the alloy material may be homogenized at a temperature of 600.degree. C. to 1200.degree. C. prior to the above step (b). In addition, the resulted magnet powder may be further heat-treated at a temperature of 300.degree. C. to 1000.degree. C. to further improve the magnetic properties.
The manufacturing conditions and so on for the above process will be hereinafter explained.
(1) R--Fe--B alloy:
The R--Fe--B alloy material to be used may be usually in the form of ingots or in bulk, but may be in other forms such as flakes or powders. The alloy material should have a composition of 8 to 30 atomic percent of R; 3 to 15 atomic percent of B; 0.01 to 5.0 atomic percent of at least one of Al, Si and V; balance Fe and unavoidable impurities.
The reasons for the inclusion of the above elements and the numerical limitations are the same as described as to the permanent magnet powder. Therefore, a part of Fe may be substituted by 0.01 atomic percent to 40 atomic percent of Co as described previously. In addition, in order to enhance squareness of the magnetization curve, at least one element of Ti, Nb, Ta, Mo and W may be added such that the total content of the element and Al, Si or V amounts to 5.0 atomic percent at the most.
Furthermore, Al, Si and V may be deleted and Ga, Zr or Hf may be added instead. More specifically, the magnet alloy material may contain:
(i) 0.001 atomic percent to 5.0 atomic percent of Ga,
(ii) 0.001 atomic percent to 5.0 atomic percent of Ga and 0.01 atomic percent to 3.0 atomic percent of one or more of Zr and Hf, or
(iii) 0.01 atomic percent to 3.0 atomic percent of one or more of Zr and Hf.
If the above modified R--Fe--B alloy is used, the magnetic anisotropy of the R--Fe--B magnet alloy can be further improved.
(2) Homogenization process
It is not necessarily required to homogenize the R--Fe--B alloy, but if homogenized, the resulting magnet powder exhibits more uniform magnetic properties. The homogenizing temperature is within the range or between 600.degree. C. to 1200.degree. C., preferably from 1050.degree. C. to 1200.degree. C. If the homogenizing temperature is less than 600.degree. C., the homogenization process becomes time-consuming, so that the industrial productivity deteriorates. On the other hand, if the temperature exceeds 1200.degree. C. the alloy will melt.
(3) Atmosphere in the temperature elevation process:
The temperature elevation step from room temperature to the temperature of 750.degree. C. to 950.degree. C. should be carried out in a hydrogen atmosphere. If the step is carried out in the above atmosphere, the reaction (1) occurs uniformly without causing fluctuations in phase transformation when compared with a vacuum or an argon atmosphere.
(4) Treating temperature in a hydrogen atmosphere and in a vacuum:
When the R--Fe--B alloy is kept in a hydrogen atmosphere at 500.degree. C. to 1000.degree. C., the phase transformation as indicated in the reaction (1) occurs, and when the alloy is then held in a vacuum at the same temperature, the phase transformation as indicated in the reaction (2) occurs. As a result, an aggregated structure of recrystallized grains is obtained. The phase transformations of the reactions (1) and (2) occur particularly at 750.degree. C. to 950.degree. C., and the aggregated structure of recrystallized grains thus obtained exhibits superior magnetic properties. Therefore, the treating temperature in a hydrogen atmosphere and in a vacuum is set to 750.degree. C. to 950.degree. C.
(5) Regenerative material:
Since the reaction (2) is endothermic, the temperature fluctuates during its lowering even though the temperature is maintained at a constant temperature ranging between 750.degree. C. to 950.degree. C. in order to prevent such fluctuation, the furnace temperature may be controlled during the phase transformation indicated by the reaction (2), but such a control is very difficult to attain on an industrial scale since special control equipment is required, and manufacturing costs are therefore increased unduly.
Therefore, in the present invention, the R--Fe--B alloy material is heated together with the regenerative material and held at a constant temperature of between 750.degree. C. and 950.degree. C. With this procedure, even though the endothermic reaction (2) occurs, the holding temperature or the R--Fe--B alloy material does not decrease due to the heat-conserving effect of the regenerative material.
The regenerative material should be a material which has a great heat content and a high melting point, and does not react with the R--Fe--B alloy material in a hydrogen atmosphere or in a vacuum. In particular, ceramics such as alumina, magnesia and zirconia, or a metal having a high melting point such as tungsten, molybdenum or stainless steel can be preferably employed. The regenerative material should be in a form separable from the R--Fe--B magnet powder, and may be in the form of plates, blocks, lumps and balls.
The method of preventing the holding temperature from lowering by using the regenerative material will be hereinafter described with reference to the accompanying drawings,
In FIGS. 3 and 4, R--Fe--B alloy ingots 2 in the form of blocks and regenerative materials in the form of bails 1 or plates 5 are both held in a vessel 3 arranged in a heating furnace 4, and the atmosphere in the heating furnace 4 is converted to a hydrogen atmosphere. Then, the R--Fe--B alloy ingot is subjected to hydrogenation while maintaining the furnace at a constant temperature of between 750.degree. C. and 950.degree. C. Subsequently, the furnace 4 is evacuated to carry out dehydrogenation. However, the regenerative materials 1 or 5, having high heat contents, are great are held in the vessel, and hence even though the endothermic reaction occurs in the dehydrogenation process, the holding temperature can be maintained constant without causing any fluctuation. Therefore, the reduction and variation of the magnetic properties can positively be prevented.
The invention will now be described in more detail by way of the following examples.
EXAMPLE 1
As shown in Tables 1-1 to 1-5, alloy ingots containing at least one of Ga, Zr and Hf as well as alloy ingots containing no Ga, Zr and Hf were prepared by means of plasma-melting and casting, and were then homogenized in an argon gas atmosphere at a temperature of 1120.degree. C. For 40 hours. The ingots thus homogenized were crushed into alloy materials of about 20 mm in size. Then the alloy materials were heated in a hydrogen atmosphere of 1 atm to elevate their temperatures from the room temperature to 850.degree. C., and were heat-treated by keeping them in the hydrogen atmosphere at 850.degree. C. for four hours. Thereafter, the alloy materials were subjected to dehydrogenation at 830.degree. C. until the pressure reached a vacuum of 1.times.10.sup.-1 torr, and argon gas was then introduced to effect a rapid quenching. The materials were heat-treated in an argon gas atmosphere at 650.degree. C. after the hydrogen treatment was completed. Then, the obtained alloy materials were crushed in mortars to produce magnet powders 1 to 28 of the invention, comparative magnet powders 1 to 11 and a prior art magnet powder 1. In addition, a part of the material alloy which was used to produce the prior art magnet powder 1 was subjected to hot pressing in a vacuum of 1.times.10.sup.-3 torr at 680.degree. C. until the density ratio was decreased to 98%, and was further subjected to plastic working at 750.degree. C. until the height was reduced to 1/4 thereof. This bulk material was then crushed so as to have an average particle size of 30 .mu.m and a prior art magnet powder 2 was thus obtained.
The magnet powders 1 to 28 of the invention, the comparative magnet powders 1 to 11 and the prior art; magnet powders 1 and 2 were then subjected to the following evaluation test. With respect to each magnet powder, the average size of the recrystallized grains and the amount (percent by volume) of the recrystallized grains for which a ratio of the greatest dimension to the smallest dimension is less than 2 was measured. In addition, these magnet powders were subjected to sieving to obtain magnet powders having particle sizes of 50 .mu.m to 420 .mu.m. Then, 100 g of each magnet powder thus obtained was subjected to an anticorrosion test by leaving it in an atmosphere of humidity of 95% and temperature of 80.degree. C., and the percent change in weight due to oxidation of magnet powder after 1000 hours of the anticorrosion test was measured. The results are set forth in Tables 1-1 to 1-5.
Furthermore, the R--Fe--B magnet powder 3 of the invention was selected and observed by a transmission electron microscope. FIG. 1 is a photomicrograph of the powder. As will be seen from FIG. 1, it is found that recrystallized grains of R.sub.2 Fe.sub.14 B phase having an average recrystallized grain size of 0.3 .mu.m exists uniformly, that about 90% by volume of the recrystallized grains are the ones for which the ratio of the greatest dimension (b) to the smallest dimension (a) is less than 2, and that the magnet powder has an aggregated structure of recrystallized grains consisting essentially of recrystallized grains of R.sub.2 Fe.sub.14 B phase.
Each of the magnet powders 1 to 28 of the invention, the comparative magnet powders 1 to 11 and the prior art magnet powders 1 and 2 was blended with 3.0% by weight of epoxy resin, and was subsequently subjected to pressing under a molding pressure of 6 ton/cm.sup.2 in a magnetic field of 25 KOe or on the absence of the magnetic field. The resulting compacts were held at 120.degree. C. for 2 hours to solidify the resin, and bonded magnets 1 to 28 of the invention, comparative bonded magnets 1 to 11 and prior art bonded magnets 1 and 2 were thus produced. The magnetic properties of the obtained bonded magnets were measured for evaluation.
It is seen from Tables 1-1 to 1-5 that the bonded magnets 1 to 28, which were obtained by molding in a magnetic field the permanent magnet powders containing at least one of Ga, Zr and Hf, are superior in magnetic properties, particularly in maximum energy product (BH).sub.max and residual magnetic flux density Br, to the bonded magnets molded in the absence of a magnetic field, and have a superior magnetic anisotropy. However, as will be seen from the comparative bonded magnets 1 to 11, when Ga, Zr or Hf content of the magnet powder falls outside the range of the invention, the magnetic properties are lowered unduly. In addition, the prior art magnet powder 1, which contained no Ga, Zr and Hf, does not exhibit a sufficient magnetic anisotropy or corrosion resistance in the case where the manufacturing conditions are the same. Furthermore, the prior art magnet powder 2, in which the recrystallized grains were formed flat by means of hot plastic working and the amount of the recrystallized grains which had the ratio of the greatest dimension to the smallest dimension of less than 2 were about 40% by volume, is not so inferior in magnetic anisotropy to the magnet powders 1 to 28 of the invention, but the percent change in weight due to anticorrosion test is increased unduly, resulting in deterioration in corrosion resistance.
EXAMPLE 2
R--Fe--B alloy ingots, which contained at least one of Ga, Zr and Hf and further contained at least one of Al, V and Si as shown in Tables 2-1 and 2-2, were prepared, and the same procedures as in EXAMPLE 1 were repeated to produce permanent magnet powders 29 to 38 of the invention and comparative magnet powders 12 to 14. With respect to each magnet powder thus obtained, the percent by volume of the recrystallized grains for which the ratio of the greatest dimension to the smallest dimension was less than 2 were measured, and then the percent change in weight: due to the anticorrosion test was similarly measured. Subsequently, the permanent magnet powders were subjected to pressing in a magnetic field or in the absence of the magnetic field to produce bonded magnets, and their magnetic properties were measured. The results are set forth in Tables 2-1 and 2-2.
It is seen from Tables 2-1 and 2-2 that when at least one of Al, V and Si was further added in a total amount of 0.01 to 2.0 atomic percent, the maximum energy product can be further improved, and the resulting magnet exhibits a better magnetic anisotropy.
EXAMPLE 3
As shown in Tables 3-1, to 3-5, R--Fe--Co--B alloy ingots containing at least one of Ga, Zr and Hf as well as R--Fe--Co--B alloy ingots containing no Ga, Zr and Hf and were prepared by means of plasma-melting and casting, and were then homogenized in an argon gas atmosphere at a temperature of 1120.degree. C. for 40 hours. The ingots thus homogenized were crushed into alloy materials of about 20 mm in size. Then the alloy materials were heated in a hydrogen atmosphere of 1 atm to elevate their temperatures from room temperature to 850.degree. C., and were heat-treated by keeping them in the hydrogen atmosphere at 850.degree. C. for four hours. Thereafter, the alloy materials were subjected to dehydrogenation at 830.degree. C. until the pressure reached a vacuum of 1.times.10.sup.-1 torr, and argon gas was then introduced to effect a rapid quenching.
The materials thus obtained were crushed in mortars to produce magnet powders 39 to 74 of the invention, comparative magnet powders 15 to 24 and a prior art magnet powder 3. Each magnet powder had an average particle size of 30 .mu.m. In addition, a part of the material alloy which was used to produce the prior art magnet powder 3 was subjected to hot pressing in a vacuum of 1.times.10.sup.-3 torr at 660.degree. C. until the ratio of density was decreased to 98%, and was further subjected to plastic working at 750.degree. C. until the height was reduced to 1/4 thereof. This bulk material was then crushed so as to have an average particle size of 30 .mu.m, and a prior art magnet powder 4 was thus obtained.
The R--Fe--Co--B magnet powders 39 to 74 of the invention, the comparative magnet powders 15 to 24 and the prior art magnet powders 1 and 2 were then subjected to the following evaluation test. With respect to each magnet powder, the average size of the recrystallized grains and the amount (percent by volume) of the recrystallized grains for which a ratio of the greatest dimension to the smallest dimension is less than 2 were measured. In addition, these magnet powders were subjected to sieving to obtain magnet powders of 50 .mu.m to 420 .mu.m. Then, 100 g of each magnet powder thus obtained was subjected to an anticorrosion test by leaving it in an atmosphere of humidity of 95% and temperature of 80.degree. C., and the percent change in weight due to oxidation of magnet powder after 1000 hours of the anticorrosion test was measured. The results are set forth in Tables 3-1 to 3-6.
Furthermore, the magnet powder 63 of the invention was selected and observed by a transmission electron microscope. FIG. 2 is a photomicrograph of the powder. As will be seen from FIG. 2, it is found that recrystallized grains of R.sub.2 (Fe,Co).sub.14 B inter-metallic compound phase having an average recrystallized grain size of 0.3 .mu.m exists uniformly, that about 90% by volume of the recrystallized grains are the ones for which the ratio of the greatest dimension (b) to the smallest dimension (a) is less than 2, and that the magnet powder has an aggregated structure of recrystallized grains consisting essentially of recrystallized grains of the R.sub.2 (Fe,Co).sub.14 B please.
Each of the magnet powders 39 to 74 of the invention, the comparative magnet powders 15 to 24 and the prior art magnet powders 3 and 4 was blended with 3.0% by weight of epoxy resin, and was subsequently subjected to pressing under a molding pressure of 6 ton/cm.sup.2 in a magnetic field of 25 KOe or in the absence of the magnetic field. The resulting compacts were held at 120.degree. C. for 2 hours to solidify the resin, and bonded magnets 39 to 74 of the invention, comparative bonded magnets 15 to 24 and prior art bonded magnets 3 and 4 were thus produced.
The magnetic properties of the obtained bonded magnets were then measured for evaluation.
It is seen from Tables 3-1 to 3-4 that the bonded magnets 39 to 74, obtained by molding in a magnetic field the permanent magnet powders are superior in magnetic properties, particularly in maximum energy product (BH).sub.max and residual magnetic flux density Br, to the bonded magnets obtained by molding in the absence of a magnetic field, and hence the R--Fe--Co--B magnet powders 39 to 74 of the invention have a superior magnetic anisotropy. On the other hand, as will be seen from Tables 3-5 and 3-6, the comparative bonded magnets 15 to 24 have a reduced magnetic anisotropy and are inferior in magnetic properties.
In addition, the prior art magnet powder 3, which contained no Ga, Zr and Hf, fails to exhibit a sufficient magnetic anisotropy or corrosion resistance although the manufacturing conditions are the same. Furthermore, the prior art magnet powder 4, in which the recrystallized grains were formed flat by means of hot plastic working, and the amount of the recrystallized grains which had the ratio of the greatest dimension to the smallest dimension of less than 2, were about 40% by volume, is not so inferior in magnetic anisotropy to the magnet powders 39 to 74 of the invention, but the resistance to the corrosion is substantially lowered since the percent of change in weight in the anticorrosion test is great.
EXAMPLE 4
R--Fe--Co--B alloy ingots, which contained at least one of Ga, Zr and Hf and further contained at least one of Al, V and Si, as shown in Tables 4-1 and 4-2, were prepared, and the same procedures as in EXAMPLE 3 were repeated to produce permanent magnet powders 75 to 84 of the invention and comparative magnet powders 25 to 27 each having an average particle size of 30 .mu.m. With respect to each magnet powder thus obtained, the percent by volume of the recrystallized grains for which the ratio of the greatest dimension to the smallest dimension was less than 2 were measured, and then the percent change in weight due to the anti-corrosion test was similarly measured. Subsequently, the permanent magnet powders were subjected to pressing in a magnetic field or in the absence of the magnetic field to produce bonded magnets, and their magnetic properties were measured. The results are set forth in Tables 4-1 and 4-2.
It is seen from Tables 4-1 and 4-2 that when at least one of Al, V and Si is further added in a total amount of 0.01 to 2.0 atomic percent, the maximum energy product can be further improved, and the magnet exhibits a better magnetic anisotropy.
EXAMPLE 5
Magnet Powders 85 to 106 of the Invention
R--Fe--B or R--Fe--Co--B alloy ingots 85 to 106 having various compositions as shown in Table 5 were first prepared by means of plasma-melting and casting, and were homogenized in an argon gas atmosphere at a temperature of 1100.degree. C. for 40 hours.
The ingots 85 to 106 thus homogenized were formed into cubic blocks of 10 to 30 mm in size to provide alloy block ingots.
Thereafter, alumina balls of 5 mm in diameter having a purity of 99.9% by weight were prepared as regenerative materials, and, as schematically shown in FIG. 3, the block ingots 2 and the alumina balls 1 were introduced in an alumina vessel 3 such that the ratio of the weight of the alloy block ingots to the regenerative materials was 1.0. Subsequently, the vessel was introduced in a heating furnace 4 and hydrogen was introduced into the furnace until the hydrogen pressure reached 760 torr, and the temperature in the furnace was elevated. After having maintained the hydrogen atmosphere of 850.degree. C. for 3 hours, the furnace was evacuated while keeping the temperature at 850.degree. C. for 1 hour until the pressure reached 1.times.10.sup.-5 torr, and was then cooled.
Thereafter, the alloy ingots and the regenerative materials were separated from each other by sieving, and the alloy ingots were crushed in a Brown mill in an argon gas atmosphere until the average particle size was reduced to no greater than 500 .mu.m.
Thus, alloy magnet powders were obtained.
Each of the magnet powders thus obtained was blended with 3.0% by weight of epoxy resin, and was subsequently subjected to pressing under a molding pressure of 6 ton/cm.sup.2 in a magnetic field of 20 KOe or in the absence of the magnetic field. The resulting compacts were held at 120.degree. C. for 60 minutes to solidify the resin, and bonded magnets 85 to 106 were thus produced.
Subsequently, with respect to each bonded magnet, the magnetic properties such as magnetic Flux density Br, coercivities iHc, maximum energy product BHmax and squareness of the demagnetization curve Hk/iHc, in which Hk denotes a magnetic field for Br .times.0.9 on a 4.pi.-H curve, were measured for subsequent evaluation. The results are shown in Tables 6-1 to 6-3.
Comparative Powders 85 to 106
The R--Fe--B or R--Fe--Co--B alloy ingots 85 to 106 shown in Table 5 were homogenized and crushed into cubic blocks of 10 to 30 mm in size to provide alloy block ingots. Thereafter, without using the regenerative materials, only the block ingots were treated by the same procedures as that used to prepare the magnet powders 85 to 106 of the invention, and were crushed to provide alloy magnet powders. Then, the same procedures as that used to prepare the magnet powders 85 to 106 was repeated to produce bonded magnets, and their magnetic properties such as magnetic flux density Br, coercivities iHc, maximum energy product BHmax and squareness of the demagnetization curve Hk/iHc were measured for evaluation. The results are shown in Tables 7-1 to 7-3.
It is seen from Tables 6 and 7 that the bonded magnets obtained using the regenerative materials were superior in magnetic properties, particularly in coercivities and squareness the magnetization curve, to the bonded magnets obtained without using the regenerative materials.
EXAMPLE 6
Powders 107 to 112 of the Invention & Comparative Powders 107 & 108
An alloy ingot having a composition of Nd.sub.12.4 Pr.sub.0.2 Co.sub.15.5 Al.sub.0.5 Fe.sub.balance was cut into cubes of 15 mm in size to provide alloy block ingots, and these ingots were homogenized in an argon gas atmosphere at 1150.degree. C. for 20 hours.
Furthermore, stainless steel plates 5 mm thick having a purity of 99.9% by weight were prepared as regenerative materials, and, as schematically shown in FIG. 4, the block ingots 2 and the stainless steel plates 5 were introduced in a vessel 3 such that the ratio of the weight of the regenerative materials to the alloy block ingots was 3.0. Subsequently, the vessel was introduced in a heating furnace 4, and was heat-treated for 3 hours under the hydrogenation conditions as shown in Table 8. Then, the dehydrogenation was carried out under the conditions as shown in Table 8 for 1 hour to cool them. Thereafter, the stainless steel regenerative materials were removed, and the resulting alloy block ingots were crushed in a disk mill in an argon gas atmosphere until the average particle size was reduced to no than 500 .mu.m. Thus, alloy magnet powders were obtained.
Each of the magnet powders thus obtained was blended with 2.0% by weight of epoxy resin, and was subsequently subjected to pressing under a molding pressure of 6 ton/cm.sup.2. The resulting compacts were held at 120.degree. C. for 60 minutes to solidify the resin, and isotropic bonded magnets were thus produced. The magnetic properties of the resulted bonded magnets are set forth in Table 8.
As will be seen from Table 8, the isotropic bonded magnet manufactured using the magnet powder, which was produced by keeping the temperature of hydrogenation and dehydrogenation at 750.degree. C. to 950.degree. C., is superior in both the coercivity iHc and squareness Hk/iHc of the demagnetization curve, but if the temperature for the hydrogenation and dehydrogenation is less than 750.degree. C., sufficient coercivities iHc cannot be obtained. On the other hand, if the temperature exceeds 950.degree. C., the magnetic properties are reduced unduly. Furthermore, it is found that not only the nonmetal material such as ceramics but also heat-resistant alloys such as stainless steel can be employed as the regenerative material.
EXAMPLE 7
Powders 113 to 128 of the Invention
R--Fe--B or R--Fe--Co--B alloy ingots 113 to 128 having various compositions as shown in Table 9 were first prepared by means of plasma-melting and casting, and the same procedures as in EXAMPLE 5 were repeated to alloy magnet powders and bonded magnets 113 to 128. The magnetic properties of the resulting bonded magnets are shown in Tables 10-1 and 10-2.
Comparative Powders 113 to 128
As was the case with EXAMPLE 5, the R--Fe--B or R--Fe--Co--B alloy ingots shown in Table 9 were homogenized and crushed into cubic blocks of 10 to 30 mm in size to provide alloy block ingots. Thereafter, the same procedures as in the comparative methods in EXAMPLE 5 were repeated to provide bonded magnets, and their magnetic properties were measured for evaluation. The results are shown in Tables 11-1 and 11-2.
It is seen from Tables 11-1 and 11-2 that when the ingots were subjected to hydrogenation and dehydrogenation using the regenerative materials, the resulting anisotropic bonded magnets obtained by the pressing in the presence of the magnetic field and the isotropic bonded magnets obtained by the pressing in the absence of the magnetic field are both excellent. Therefore, the alloy magnet powder has high magnetic properties.
Furthermore, the bonded magnets obtained from the magnet powder containing Ga, Zr or Hf arc superior in magnetic anisotropy to the bonded magnets obtained from the magnet powder without such elements. Therefore, the addition of Ga, Zr or Hf improves the magnetic anisotropy of the magnet powder.
EXAMPLE 8
Powders 129 to 134 of the Invention & Comparative Powders 129 & 130
An alloy ingot having a composition of Nd.sub.12.4 Pr.sub.0.2 Fe.sub.balance Co.sub.10.1 B.sub.6.0 Ga.sub.0.5 was cut into cubes off 15 mm in size to provide alloy block ingots, and these ingots were homogenized in an argon gas atmosphere at 1150.degree. C. for 20 hours.
Furthermore, magnesia plates of 5 mm in thickness having a purity of 99.9% by weight were prepared as regenerative materials, and, as schematically shown in FIG. 4, the block ingots 2 and the magnesia plates 5 were introduced in a vessel 3 such that the ratio of the weight of the regenerative materials to the alloy block ingots was 2.0. Subsequently, the vessel was introduced in a heating furnace 4, and hydrogen was introduced into the furnace until the hydrogen pressure reached 1 atm. Then, the temperature in the furnace was elevated and heat-treatment was carried out for 3 hours under the hydrogenation conditions as shown in Table 5. Then, the dehydrogenation was carried out for 1 hour until the pressure reached 1.times.10.sup.-5 torr to cool them. Thereafter, the magnesia plate regenerative materials were removed, and the resulting alloy block ingots were crushed in a disk mill in an argon gas atmosphere until the average particle size was reduced to no greater than 500 .mu.m. Thus, alloy magnet powders were obtained.
Each of the magnet powders thus obtained was blended with 2.0% by weight of epoxy resin, and was subsequently subjected to pressing under a molding pressure of 6 ton/cm.sup.2 in a magnetic field of 20 KOe. The resulting compacts were held at 120.degree. C. for 60 minutes to solidify the resin, and isotropic bonded magnets were thus produced. The magnetic properties of the resulting bonded magnets are set forth in Table 12.
As will be seen from Table 12, the anisotropic bonded magnet manufactured using the magnet powder, which was produced by keeping the temperature of hydrogenation and dehydrogenation at 750.degree. C. to 950.degree. C., is superior in magnetic properties, particularly in maximum energy product (BH)max, and the magnet exhibits a better magnetic anisotropy.
TABLE 1-1__________________________________________________________________________Magnet R--Fe--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) c magnetic of bonded magnetsof the Total d (vol f field upon Br iHe BH.sub.maxinvention Nd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________1 12.1 0.3 -- -- 6.0 0.01 -- -- 0.01 Other 0.2 95 0.295 Present 7.5 11.4 12.8 Absent 6.0 11.4 8.02 12.0 0.5 -- -- 6.0 0.1 -- -- 0.1 Other 0.4 80 0.290 Present 8.5 14.3 15.1 Absent 6.1 14.5 8.13 12.0 -- 0.5 -- 6.0 0.5 -- -- 0.5 Other 0.3 90 0.274 Present 8.5 14.6 15.4 Absent 6.3 14.7 9.04 11.9 0.5 -- -- 5.9 5.0 -- -- 5.0 Other 0.5 80 0.152 Present 8.3 10.7 15.1 Absent 5.7 11.0 7.05 12.1 -- 0.2 0.1 6.0 -- 0.01 -- 0.01 Other 0.2 90 0.288 Present 6.5 10.0 9.1 Absent 5.9 10.0 7.66 12.0 -- 0.2 0.2 5.9 -- 0.1 -- 0.1 Other 0.4 90 0.275 Present 7.8 8.5 12.5 Absent 6.1 8.8 8.07 12.1 -- 0.2 0.1 6.0 -- 1.0 -- 1.0 Other 0.5 85 0.182 Present 7.8 9.3 12.0 Absent 6.0 9.5 7.78 12.0 -- 0.2 0.2 6.0 -- 5.0 -- 5.0 Other 1.0 100 0.177 Present 7.5 7.4 11.3 Absent 5.8 7.3 7.09 12.0 0.2 0.2 -- 6.1 -- -- 0.01 0.01 Other 0.3 85 0.280 Present 6.5 9.8 9.4 Absent 5.8 9.9 7.3__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 1-2__________________________________________________________________________Magnet R--Fe--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) magnetic of bonded magnetsof the Total d c f field upon Br iHe BH.sub.maxinvention Nd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________10 11.9 0.1 0.3 -- 5.9 -- -- 0.1 0.1 Other 0.4 80 0.254 Present 7.6 9.5 1.5 Absent 6.0 9.8 7.511 12.2 0.2 0.2 -- 6.0 -- -- 1.0 1.0 Other 0.4 90 0.201 Present 6.4 9.1 9.2 Absent 5.8 9.5 7.012 12.0 0.2 0.2 -- 6.0 -- -- 5.0 5.0 Other 0.5 85 0.179 Present 7.3 8.3 11.0 Absent 5.5 8.5 6.213 12.0 0.3 -- -- 6.1 -- 0.5 0.5 1.0 Other 0.6 95 0.198 Present 8.2 9.8 14.4 Absent 5.8 10.1 7.214 11.9 0.5 -- -- 6.0 -- 2.3 2.5 4.8 Other 1.0 75 0.180 Present 8.1 8.3 13.8 Absent 5.4 8.4 6.215 12.6 -- -- -- 6.0 0.5 0.5 0.5 1.5 Other 0.5 90 0.210 Presnet 8.3 14.7 15.0 Absent 5.7 14.6 7.416 12.4 -- -- -- 6.1 0.5 0.5 -- 1.0 Other 0.4 80 0.266 Present 8.5 14.3 15.6 Absent 5.7 14.4 7.517 12.1 -- -- -- 6.0 0.5 -- 0.5 1.0 Other 0.3 70 0.258 Present 8.5 14.0 16.0 Absent 5.8 14.1 7.518 13.6 -- 0.2 -- 6.1 0.5 -- 0.3 0.8 Other 1.0 80 0.358 Present 7.5 15.5 12.1 Absent 5.3 15.6 6.1__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 1-3__________________________________________________________________________Magnet R--Fe--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) magnetic of bonded magnetsof the Total d c f field upon Br iHe BH.sub.maxinvention Nd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________19 13.6 -- 0.2 -- 6.1 0.5 -- 0.3 0.8 Other 1.5 50 0.379 Present 7.3 15.0 11.5 Absent 5.2 15.3 6.020 20.0 -- -- -- 7.0 1.0 -- 0.1 1.1 Other 0.8 85 0.985 Present 6.9 11.9 10.5 Absent 4.8 12.0 5.021 15.0 -- -- -- 8.0 0.6 -- 0.1 0.7 Other 0.5 85 0.626 Present 7.1 12.4 11.0 Absent 5.2 12.6 5.722 16.0 -- -- -- 3.0 -- -- 0.1 0.1 Other 0.4 70 0.687 Present 6.7 9.5 8.6 Absent 3.1 9.7 2.223 13.0 -- -- -- 10.0 -- 0.1 0.1 0.2 Other 0.5 75 0.360 Present 7.3 9.3 10.4 Absent 5.2 9.4 4.624 14.0 -- -- -- 20.0 -- 0.1 0.1 0.2 Other 1.0 90 0.575 Present 8.2 5.7 10.0 Absent 3.5 5.9 2.125 10.0 -- -- -- 7.0 2.0 -- -- 2.0 Other 0.6 80 0.186 Present 9.2 9.3 11.4 Absent 5.7 9.5 5.026 13.0 -- -- -- 6.0 0.5 -- -- 0.5 Other 5.0 95 0.525 Present 7.7 10.7 11.0 Absent 4.8 10.8 4.727 13.0 -- -- -- 6.0 0.5 -- -- 0.5 Other 10.0 85 0.608 Present 8.2 6.4 10.2 Absent 4.2 6.4 2.528 13.0 -- -- -- 6.0 0.5 -- -- 0.5 Other 20.0 90 0.974 Present 8.6 5.1 10.0 Absent 4.0 5.2 2.0__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 1-4__________________________________________________________________________Compar- R--Fe--B permanent magnet powder Presence of Magnetic propertiesative Composition (Atomic %) d f magnetic of bonded magnetsmagnet Total d (vol (wt field upon Br iHc BH.sub.maxpowder Nd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) %) %) Pressing (KG) (KOe) (MGOe)__________________________________________________________________________1 12.1 0.4 -- -- 5.6 7.0 -- -- 7.0 Other 1.2 80 0.113 Present 6.2 9.7 8.0 Absent 5.5 9.9 6.02 12.3 0.3 -- -- 6.0 -- 7.0 -- 7.0 Other 0.6 80 0.104 Present 6.1 4.2 4.2 Absent 5.1 4.4 4.13 12.2 0.3 -- -- 6.1 -- -- 7.0 7.0 Other 0.5 90 0.108 Present 5.5 5.1 4.2 Absent 5.0 5.0 3.94 11.9 0.4 -- -- 6.0 -- 3.5 3.4 6.9 Other 0.7 85 0.096 Present 6.0 7.3 7.7 Absent 5.1 7.3 5.45 12.2 0.3 -- -- 6.0 3.5 3.5 -- 7.0 Other 1.0 80 0.109 Present 6.7 12.1 8.6 Absent 5.5 12.3 7.06 12.2 -- -- -- 6.1 0.4 -- -- 0.4 Other 0.01 95 0.052 Present 2.5 0.2 <1 Absent 2.0 0.3 <17 12.4 -- -- -- 6.0 0.4 -- -- 0.4 Other 22 95 1.837 Present 4.2 1.1 < 1 Absent 2.3 1.3 <18 25.0 -- -- -- 7.0 1.0 -- 0.2 1.2 Other 0.6 90 1.522 Present 1.8 1.3 <1 Absent 1.5 1.5 <19 8.0 -- -- -- 7.0 2.0 -- -- 2.0 Other 0.3 85 0.120 Present 3.5 0.2 <1 Absent 2.0 0.2 <1__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention.)
TABLE 1-5__________________________________________________________________________R-- Fe--B permanent magnet powder Presence of Magnetic propertiesComposition (Atomic %) magnetic of bonded magnets Total d c f field upon Br iHc BH.sub.maxNd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________Compar-ativemagnetpowder10 16.0 -- -- -- 2.0 -- -- 0.1 0.1 Other 2.0 80 1.024 Present 2.5 0.2 <1 Absent 1.2 0.2 <111 14.0 -- -- -- 25.0 -- 0.1 0.1 0.2 Other 1.0 85 0.443 Present 3.3 0.2 <1 Absent 2.0 0.3 <1Priorartmagnetpowder1 15.0 -- -- -- 8.0 -- -- -- -- Other 0.4 90 0.745 Present 5.4 14.1 6.2 Absent 5.4 14.3 6.12 15.0 -- -- -- 8.0 -- -- -- -- Other 0.8 40 1.142 Present 6.6 10.5 9.3 Absent 5.0 10.6 5.4__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention
TABLE 2-1__________________________________________________________________________Magnet R--Fe--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) c magnetic of bonded magnetsof the Total Total d (vol f field upon Br iHe BH.sub.maxinvention Nd B Ga Zr Hf amount Al V Si amount Fe (.mu.m) %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________29 12.6 6.0 1.0 -- -- 1.0 0.3 -- -- 0.3 Other 0.3 80 0.223 Present 8.6 13.3 16.2 Absent 6.0 13.5 7.930 12.6 6.0 1.0 -- -- 1.0 0.1 0.1 -- 0.2 Other 0.4 90 0.230 Present 8.6 12.9 16.0 Absent 6.0 13.2 7.831 12.6 6.0 1.0 -- -- 1.0 0.7 -- -- 0.7 Other 0.3 85 0.203 Present 8.5 15.5 16.1 Absent 5.9 15.4 7.432 12.6 6.0 1.0 -- -- 1.0 2.0 -- -- 2.0 Other 0.5 80 0.187 Present 8.5 13.4 16.0 Absent 5.8 13.6 7.333 12.5 6.0 1.0 -- -- 1.0 -- 0.4 -- 0.4 Other 0.1 95 0.205 Present 8.7 13.3 16.5 Absent 5.9 13.4 7.834 12.5 6.0 -- -- 0.3 0.3 -- 0.2 -- 0.2 Other 0.2 100 0.224 Present 7.8 9.6 13.0 Absent 5.8 9.8 7.035 12.5 6.0 0.5 -- -- 0.5 -- -- 0.3 0.3 Other 0.4 85 0.210 Present 8.5 14.2 16.0 Absent 6.1 14.3 8.136 12.5 6.0 0.3 0.1 -- 0.4 -- -- 0.4 0.4 Other 0.4 90 0.215 Present 8.6 13.7 16.4 Absent 5.8 14.0 7.637 12.5 6.0 0.3 -- 0.1 0.4 -- -- 2.0 2.0 Other 0.5 90 0.193 Present 8.5 13.2 15.5 Absent 5.8 13.3 7.038 12.5 6.0 0.3 -- -- 0.3 0.3 0.3 0.3 0.9 Other 0.8 80 0.196 Present 8.2 11.1 14.5 Absent 5.5 11.3 6.2__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2".
TABLE 2-2__________________________________________________________________________Compar- R--Fe--B permanent magnet powder Presence of Magnetic propertiesative Composition (Atomic %) magnetic of bonded magnetsmagnet Total d c f field upon Br iHc BH.sub.maxpowder Nd Dy Pr Tb B Ga Zr Hf amount Fe (.mu.m) (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________12 12.6 -- -- -- 6.0 0.5 -- -- 3.0Al Other 0.5 80 0.158 Present 7.8 10.3 12.1 Absent 5.8 10.5 6.613 12.6 -- -- -- 6.0 0.5 -- -- 3.0V Other 0.8 85 0.174 Present 7.3 10.1 10.5 Absent 5.7 10.4 6.314 12.6 -- -- -- 6.0 0.5 -- -- 3.0Si Other 0.5 80 0.170 Present 7.5 12.4 11.6 Absent 5.8 12.6 7.2__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention)
TABLE 3-1__________________________________________________________________________Magnet R--Fe--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) c f magnetic of bonded magnetsof the Total d (vol (wt field upon Br iHc BH.sub.maxinvention Nd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m) %) %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________39 12.6 -- -- -- 7.0 6.0 0.01 -- -- 0.01 Other 0.4 90 0.254 Present 7.6 10.3 12.0 Absent 6.0 10.5 7.940 12.4 -- -- -- 7.1 6.0 0.1 -- -- 0.1 Other 0.3 90 0.255 Present 8.6 12.4 15.7 Absent 6.2 12.4 8.141 12.4 -- -- -- 7.1 5.9 1.0 -- -- 1.0 Other 0.3 80 0.205 Present 8.7 13.3 16.5 Absent 6.4 13.6 9.342 12.5 -- -- -- 7.1 6.1 2.0 -- -- 2.0 Other 0.4 85 0.199 Present 8.5 11.5 15.1 Absent 6.1 11.4 8.043 12.5 -- -- -- 7.0 6.1 5.0 -- -- 5.0 Other 0.6 90 0.185 Present 8.3 10.8 14.2 Absent 5.8 10.8 7.344 12.5 -- -- -- 7.0 6.0 -- 0.01 -- 0.01 Other 0.2 85 0.250 Present 7.3 10.3 11.0 Absent 5.9 10.4 7.545 12.4 -- -- -- 6.9 6.0 -- 0.1 -- 0.1 Other 0.3 80 0.241 Present 8.3 8.0 14.0 Absent 5.9 8.2 7.146 12.4 -- -- -- 7.0 6.1 -- 1.0 -- 1.0 Other 0.2 90 0.166 Present 7.0 8.4 10.5 Absent 5.9 8.7 7.147 12.6 -- -- -- 7.0 6.0 -- 2.0 0.1 2.1 Other 0.4 75 0.156 Present 8.2 8.5 13.5 Absent 5.7 8.5 6.6__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 3-1__________________________________________________________________________Mag-net Presencepow- ofder R--Fe--B permanent magnet powder magnetic Magnetic propertiesof the Composition (Atomic %) c f field of bonded magnetsinven- Total d (vol (wt upon Br iHc BH.sub.maxtion Nd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m) %) %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________48 12.5 -- -- -- 7.0 6.1 -- 4.8 0.1 4.9 Other 0.4 80 0.124 Present 8.0 7.3 12.8 Absent 5.4 7.6 6.049 12.4 -- -- -- 7.0 6.2 -- -- 0.01 0.01 Other 0.2 85 0.265 Present 7.7 10.6 12.0 Absent 6.1 10.7 7.650 12.3 -- -- -- 7.0 5.9 -- -- 0.1 0.1 Other 0.2 90 0.250 Present 8.5 9.5 15.1 Absent 5.9 9.8 7.551 12.5 -- -- -- 6.8 6.0 -- -- 1.0 1.0 Other 0.6 85 0.198 Present 7.4 8.2 11.9 Absent 5.9 8.5 7.452 12.4 -- -- -- 7.1 6.1 -- 0.1 2.0 2.1 Other 1.2 85 0.188 Present 8.4 8.7 15.0 Absent 5.7 8.7 7.153 12.6 -- -- -- 7.1 6.1 -- 0.1 4.8 4.9 Other 1.0 80 0.190 Present 8.4 7.3 14.2 Absent 5.3 7.2 6.354 12.2 -- -- 0.3 17.0 6.0 0.001 0.001 0.001 0.003 Other 0.2 90 0.153 Present 7.5 10.5 12.4 Absent 6.0 10.8 7.855 12.5 -- 0.3 -- 11.5 6.0 0.5 0.5 0.5 1.5 Other 0.5 80 0.163 Present 7.8 10.3 12.1 Absent 5.8 10.5 6.856 12.2 -- -- -- 16.5 6.0 0.4 -- -- 0.4 Other 0.2 85 0.150 Present 8.8 13.6 17.5 Absent 6.0 13.8 7.9__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/(smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 3-3__________________________________________________________________________Magnet R--Fe--Co--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) c f magnetic of bonded magnetsof the Total d (vol (wt field upon Br iHc BH.sub.maxinvention Nd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m) %) %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________57 12.2 -- -- -- 16.8 6.0 0.3 -- 0.1 0.4 Other 0.2 85 0.135 Present 9.0 13.0 18.0 Absent 6.1 13.5 8.058 10.0 -- -- -- 5.0 8.1 1.5 -- -- 1.5 Other 0.1 85 0.155 Present 8.8 8.6 12.5 Absent 5.5 8.8 4.659 15.1 -- -- -- 11.5 8.0 0.6 -- 0.1 0.7 Other 0.3 100 0.475 Present 7.2 12.0 11.2 Absent 5.3 12.5 5.860 20.0 -- -- -- 11.8 7.0 1.0 -- 0.1 1.1 Other 0.4 90 0.643 Present 6.9 12.3 10.6 Absent 4.9 12.5 5.061 12.2 -- 0.2 -- 0.1 6.0 0.5 -- -- 0.5 Other 0.2 90 0.260 Present 8.6 14.4 15.7 Absent 6.3 14.5 8.262 12.4 0.2 -- -- 5.2 6.0 0.5 -- -- 0.5 Other 0.4 95 0.244 Present 8.6 14.5 16.0 Absent 6.1 14.6 8.163 12.5 -- -- 0.1 11.5 6.0 0.5 -- -- 0.5 Other 0.3 90 0.205 Present 8.8 14.0 16.5 Absent 6.1 14.3 8.264 12.2 -- 0.2 -- 30.0 6.0 0.5 0.05 -- 0.55 Other 0.1 85 0.108 Present 7.5 9.8 11.8 Absent 5.6 10.0 6.065 12.3 0.2 -- -- 50.0 6.0 0.4 -- -- 0.4 Other 0.5 90 0.055 Present 7.6 8.3 10.6 Absent 4.8 8.5 4.0__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 3-4__________________________________________________________________________Magnet R--Fe--Co--B permanent magnet powder Presence of Magnetic propertiespowder Composition (Atomic %) c f magnetic of bonded magnetsof the Total d (vol (wt field upon Br iHc BH.sub.maxinvention Nd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m) %) %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________66 16.0 -- -- -- 11.2 3.0 -- -- 0.1 0.1 Other 0.3 80 0.488 Present 8.5 9.80 10.8 Absent 3.1 10.1 2.167 12.1 -- -- 0.5 6.4 10.4 -- 0.5 0.5 1.0 Other 0.5 80 0.251 Present 8.3 10.1 14.0 Absent 5.6 10.3 6.868 14.0 -- -- -- 11.0 20.0 -- 0.1 0.1 0.2 Other 0.4 80 0.394 Present 8.2 6.5 10.4 Absent 3.5 6.7 2.169 13.2 -- 0.3 -- 11.5 6.1 0.5 -- 0.2 0.7 Other 0.8 60 0.224 Present 7.6 16.0 12.0 Absent 5.4 16.2 6.270 13.2 -- 0.3 -- 11.5 6.1 0.5 -- 0.2 0.7 Other 1.0 50 0.305 Present 7.2 15.4 10.2 Absent 5.2 15.5 5.571 12.4 -- -- 0.2 11.5 6.0 0.5 -- 0.1 0.6 Other 0.05 90 0.185 Present 8.5 13.1 15.6 Absent 6.0 13.5 8.072 16.0 -- -- -- 11.3 6.0 0.5 -- -- 0.5 Other 5.0 85 0.466 Present 7.9 11.2 11.0 Absent 4.9 11.5 4.873 16.0 -- -- -- 11.3 6.0 0.5 -- -- 0.5 Other 10.0 70 -- Present 8.3 6.6 10.3 Absent 4.2 6.8 2.874 16.0 -- -- -- 11.3 6.0 0.5 -- -- 0.5 Other 20.0 80 -- Present 8.6 5.4 10.1 Absent 3.2 5.5 1.2__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 3-5__________________________________________________________________________Compar- R-- Fe--Co--B permanent magnet powderative Composition (Atomic %)magnet Total dpowder Nd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m)__________________________________________________________________________15 12.5 -- 0.5 -- 7.0 6.0 0.5 -- 0.5 1.0 Other 0.0116 12.5 -- 0.4 -- 7.0 6.0 0.5 0.5 0.5 1.5 Other 2317 12.3 -- -- -- 7.1 6.1 7.9 -- -- 7.9 Other 0.518 12.4 -- -- -- 7.2 5.9 -- 7.0 0.2 7.2 Other 0.619 12.5 -- -- -- 7.0 5.9 -- 0.2 6.7 6.9 Other 0.520 9.0 -- -- -- 16.2 7.0 2.0 -- -- 2.0 Other 2.021 25.0 -- -- -- 16.5 7.0 1.0 -- 0.2 1.2 Other 5.022 13.0 -- -- -- 55.1 7.0 1.0 -- 0.5 1.5 Other 0.523 16.0 -- -- -- 11.2 2.0 -- -- 0.1 0.1 Other 2.0__________________________________________________________________________ Compar- Presence of Magnetic properties ative magnetic of bonded magnets magnet c f field upon Br iHc BH.sub.max powder (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________ 15 85 0.040 Present 5.4 5.3 3.6 Absent 3.2 5.3 <1 16 80 1.775 Present 4.0 0.8 <1 Absent 2.2 0.7 <1 17 85 0.095 Present 6.0 10.0 7.7 Absent 5.6 10.1 6.8 18 70 0.088 Present 6.1 4.6 6.8 Absent 5.2 4.7 4.7 19 80 0.093 Present 5.8 5.4 6.3 Absent 5.1 5.5 5.0 20 90 0.104 Present 3.5 0.2 <1 Absent 2.1 0.2 <1 21 80 1.462 Present 1.6 1.6 <1 Absent 1.3 1.8 <1 22 85 0.066 Present 4.5 7.5 3.3 Absent 4.0 7.6 2.5 23 85 0.944 Present 2.7 0.2 <1 Absent 1.3 0.3 <1__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention
TABLE 3-6__________________________________________________________________________ Presence ofR-- Fe--Co--B permanent magnet powder magnetic Magnetic propertiesComposition (Atomic %) c f field of bonded magnets Total d (vol (wt upon Br iHc BH.sub.maxNd Tb Dy Pr Co B Ga Zr Hf umount Fe (.mu.m) %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________Compar-ativemagnetpowder24 14.0 -- -- -- 11.2 21.7 -- 0.1 0.1 0.2 Other 1.0 90 0.406 Present 3.5 0.2 <1 Absent 2.0 0.3 <1Priorartmagnetpowder3 14.5 -- 0.4 -- 7.2 6.0 -- -- -- -- Other 0.4 95 0.664 Present 5.6 14.0 6.8 Absent 5.5 14.2 6.54 14.5 -- 0.4 -- 7.2 6.0 -- -- -- -- Other 1.0 40 1.038 Present 7.1 11.2 10.2 Absent 5.1 11.3 5.5__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention)
TABLE 4-1__________________________________________________________________________Magnet R--Fe--B permanent magnet powderpowder Composition (Atomic %)of the Total Total dinvention Nd Co B Ga Zr Hf amount Al V Si amont Fe (.mu.m)__________________________________________________________________________75 12.4 7.6 6.0 1.0 -- -- 1.0 0.1 -- -- 0.1 Other 0.276 12.5 11.3 6.0 1.0 -- -- 1.0 0.4 -- -- 0.4 Other 0.377 12.4 7.4 5.9 1.0 -- -- 1.0 -- 0.5 -- 0.5 Other 0.278 12.3 7.4 6.0 0.5 -- -- 0.5 -- -- 2.0 2.0 Other 0.479 12.3 11.4 6.0 0.1 0.1 -- 0.2 0.5 0.2 0.5 1.2 Other 0.580 12.4 11.3 6.0 -- -- 0.1 0.1 -- -- 0.4 0.5 Other 0.481 12.0 11.4 6.0 -- 1.0 1.0 2.0 0.3 -- 0.1 0.4 Other 0.382 12.1 16.8 6.0 0.2 0.1 0.1 0.4 2.0 -- -- 2.0 Other 0.283 12.2 16.5 6.0 -- -- 0.1 0.1 0.5 -- -- 0.5 Other 0.284 12.2 16.5 6.0 0.5 -- -- 0.5 0.02 0.01 0.02 0.05 Other 0.5__________________________________________________________________________ Magnet Presence of Magnetic properties powder magnetic of bonded magnets of the c f field upon Br iHc BH.sub.max invention (vol %) (wt %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________ 75 80 0.194 Present 8.9 13.2 7.6 Absent 6.1 13.3 8.2 76 90 0.186 Present 9.1 13.5 18.5 Absent 6.2 13.6 8.3 77 95 0.178 Present 8.9 10.5 17.2 Absent 6.0 10.5 8.1 78 80 0.180 Present 9.0 12.2 18.2 Absent 6.0 12.3 7.8 79 75 0.163 Present 8.9 12.3 18.0 Absent 5.8 12.5 7.6 80 80 0.173 Present 8.8 10.1 17.2 Absent 6.0 10.4 7.9 81 80 0.147 Present 8.6 11.0 17.0 Absent 5.7 11.5 7.1 82 90 0.142 Present 9.0 12.0 18.0 Absent 5.7 12.3 7.1 83 95 0.155 Present 9.1 11.4 18.2 Absent 6.1 11.8 8.0 84 90 0.197 Present 8.9 13.2 18.0 Absent 6.0 13.4 7.8__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test".
TABLE 4-2__________________________________________________________________________Com-par-ativemag- R--Fe--B permanent magnet powder Presence of Magnetic propertiesnet Composition (Atomic %) magnetic of bonded magnetspow- Total Total d (vol (wt field upon Br iHc BH.sub.maxder Nd Co B Ga Zr Hf amount Al V Si amount Fe (.mu.m) %) %) pressing (KG) (KOe) (MGOe)__________________________________________________________________________25 12.5 11.4 6.0 0.5 -- -- 0.5 3.0 -- -- 3.0 Other 0.8 80 0.144 Present 7.6 10.5 0.8 Absent 5.9 10.8 7.226 12.4 11.4 6.0 0.5 -- -- 0.5 -- 3.0 -- 3.0 Other 0.4 85 0.170 Present 7.4 10.6 10.2 Absent 5.7 10.8 6.527 12.5 11.4 6.0 0.5 -- -- 0.5 -- -- 3.0 3.0 Other 0.3 70 0.163 Present 7.6 11.3 11.8 Absent 5.8 11.5 7.3__________________________________________________________________________ "d" denotes "average size of recrystallized grains". "c" denotes "% by volume of recrystallized grains for which (greatest dimension)/smallest dimension) < 2". "f" denotes "% increase in weight after 1000 hr anticorrosion test". denotes values out of the range of the invention)
TABLE 5__________________________________________________________________________R-- Fe--Balloy Composition (Atomic %)ingots Nd Pr Dy Co B Al Si V Additional element Fe & impurities__________________________________________________________________________85 12.1 0.2 -- 16.5 6.5 -- -- -- -- other86 12.2 0.2 -- 16.4 6.4 1.0 -- -- -- other87 12.2 0.2 -- 16.5 6.5 -- 1.0 -- -- other88 12.1 0.2 -- 16.6 6.5 -- -- 1.0 -- other89 12.4 -- 0.2 -- 5.9 -- -- -- -- other90 12.5 -- 0.2 -- 6.0 1.0 -- -- -- other91 12.3 -- 0.2 -- 6.0 -- 0.6 -- -- other92 12.4 -- 0.2 -- 6.1 -- -- 0.5 -- other93 12.3 -- -- 6.0 6.5 0.5 0.5 -- -- other94 12.2 -- -- 5.9 6.5 0.5 -- 0.5 -- other95 12.2 -- -- 5.9 6.6 -- 0.5 0.5 -- other96 13.2 0.2 -- -- 6.0 0.5 0.5 -- -- other97 13.2 0.2 -- -- 6.1 1.0 -- 0.5 -- other98 13.2 0.2 -- -- 6.0 -- 1.0 0.5 -- other99 12.2 -- -- 6.5 6.4 0.2 0.3 0.5 -- other100 13.1 0.2 -- 6.5 6.0 0.5 0.3 0.3 -- other101 12.3 0.4 -- 16.7 7.0 0.5 -- -- -- other102 12.2 0.3 -- 16.7 7.0 0.5 -- -- 0.5 Nb other103 12.3 0.3 -- 16.8 7.0 0.5 -- 0.3 0.3 Ta other104 12.2 -- 0.2 11.8 6.5 -- 0.8 -- -- other105 12.3 -- 0.2 11.7 6.5 -- 0.8 -- 0.3 Mo other106 12.2 -- 0.2 11.5 6.5 -- 0.8 -- 0.2 W other__________________________________________________________________________
TABLE 6-1__________________________________________________________________________R--Fe--Bingots Magnetic property ofPowders Manufacturing conditions of R-T-B magnet alloy powder Presence of bonded magnetsof the regenerative magnetic field Br iHc BH.sub.max Squarnessinvention material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________85 Alumina ball Temperature: 850.degree. C. Temperature: 850.degree. C. Present 7.0 11.6 10.8 0.39 H.sub.2 pressure: 760 Torr Vacuum: 1 .times. 10.sup.-5 Torr Absent 6.0 11.8 8.1 0.3386 Present 6.7 14.6 9.0 0.36 Absent 6.3 14.6 9.0 0.3687 Present 6.4 13.8 9.0 0.35 Absent 6.2 14.0 8.3 0.3188 Present 6.0 10.0 8.1 0.45 Absent 5.9 10.4 8.0 0.4589 Present 6.5 10.5 9.0 0.34 Absent 5.9 10.6 7.4 0.3190 Present 6.3 15.5 9.1 0.38 Absent 6.1 15.7 8.2 0.2791 Present 6.3 11.3 8.5 0.32 Absent 6.1 11.4 7.9 0.2892 Present 5.9 9.8 7.8 0.39 Absent 5.8 10.0 7.6 0.4093 Persent 6.3 12.8 8.8 0.32 Absent 6.1 12.8 8.0 0.26__________________________________________________________________________
TABLE 6-2__________________________________________________________________________R--Fe--Bingots Magnetic property ofExamples Manufacturing conditions of R-T-B magnet alloy powder Presence of bonded magnetsof the regenerative magnetic field Br iHc BH.sub.max Squarnesspowders material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________94 Alumina ball Temperature: 850.degree. C. Temperature: 850.degree. C. Present 6.1 0.4 8.1 0.38 H.sub.2 pressure: 760 Torr Vacuum: 1 .times. 10.sup.-5 Torr Absent 6.0 10.3 8.0 0.3495 Present 6.0 9.5 8.1 0.46 Absent 6.0 9.7 8.0 0.4196 Present 6.4 10.7 9.1 0.39 Absent 6.2 10.8 8.3 0.3397 Present 5.9 9.6 7.9 0.48 Absent 5.9 9.9 7.8 0.4398 Present 6.0 10.5 8.0 0.41 Absent 5.9 10.7 7.8 0.3999 Present 5.9 10.7 7.8 0.37 Absent 5.9 11.0 7.8 0.37100 Present 6.0 11.1 7.9 0.29 Absent 5.8 11.4 7.5 0.33101 Present 6.4 13.1 8.7 0.24 Absent 6.1 13.3 8.0 0.24102 Persent 6.3 11.5 8.8 0.33 Absent 6.2 11.8 8.3 0.27__________________________________________________________________________
TABLE 6-3__________________________________________________________________________R--Fe--Bingots Magnetic property ofPowders Manufacturing conditions of R-T-B magnet alloy powder Presence of bonded magnetsof the regenerative magnetic field Br iHc BH.sub.max Squarnessinvention material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________103 Alumina ball Temperature: 850.degree. C. Temperature: 850.degree. C. Present 6.4 12.2 9.1 0.29 H.sub.2 pressure: 760 Torr Vacuum: 1 .times. 10.sup.-5 Torr Absent 6.2 12.3 8.4 0.26104 Present 6.2 12.5 8.3 0.25 Absent 6.0 12.6 7.8 0.21105 Present 6.2 11.9 8.5 0.33 Absent 6.1 12.0 8.1 0.29106 Present 6.2 12.3 8.4 0.28 Absent 6.2 12.4 8.4 0.28__________________________________________________________________________
TABLE 7-1__________________________________________________________________________R--Fe--B Magnetic property ofalloy ingots Manufacturing conditions of R--Fe--B magnet alloy Presence of bonded magnetsComparative Pegenerative magnetic field Br iHc BH.sub.max Squarnesspowders material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________85 Temperature: 850.degree. C. Temperature: 850.degree. C. Present 6.5 9.4 7.1 0.16 H.sub.2 pressure: 760 Vacuum: 1 .times. 10.sup.-5 Torr Absent 5.7 9.6 6.5 0.20 86 Present 6.3 11.3 7.0 0.13 Absent 6.0 11.5 6.1 0.12 87 Present 6.0 10.0 7.0 0.20 Absent 5.7 10.0 5.8 0.15 88 Present 5.5 7.6 5.9 0.23 Absent 5.4 7.9 5.8 0.24 89 Present 5.7 8.0 6.2 0.21 Absent 5.5 8.1 5.7 0.21 90 Present 5.8 13.7 7.1 0.21 Absent 5.3 13.8 6.0 0.18 91 Present 5.9 8.6 6.3 0.19 Absent 5.4 8.8 5.2 0.15 92 Present 5.2 5.4 5.0 0.32 Absent 5.0 5.4 4.4 0.22 93 Persent 5.9 10.3 6.5 0.16 Absent 5.7 10.5 6.1 0.17__________________________________________________________________________ denotes values out of the range of the invention
TABLE 7-2__________________________________________________________________________R--Fe--B Magnetic property ofalloy ingots Manufacturing conditions of R--Fe--B magnet alloy Presence of bonded magnetsComparative regenerative magnetic field Br iHc BH.sub.max Squarnesspowders material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________94 Temperature: 850.degree. C. Temperature: 850.degree. C. Present 5.8 8.7 6.2 0.23 H.sub.2 pressure: 760 Vacuum: 1 .times. 10.sup.-5 Torr Absent 5.7 8.6 5.3 0.14 95 Present 5.8 5.7 6.0 0.29 Absent 5.6 5.8 4.9 0.29 96 Present 5.4 6.4 5.5 0.25 Absent 5.0 6.7 4.2 0.18 97 Present 5.7 6.5 5.8 0.23 Absent 5.5 6.5 4.5 0.15 98 Present 5.5 5.3 5.3 0.26 Absent 5.2 5.5 4.2 0.20 99 Present 5.6 6.3 5.1 0.20 Absent 5.1 6.7 4.0 0.13 100 Present 5.5 7.2 4.9 0.18 Absent 5.4 7.3 4.7 0.23 101 Present 5.9 10.1 6.5 0.20 Absent 5.8 10.4 6.2 0.19 102 Persent 5.8 9.5 6.0 0.21 Absent 5.7 9.6 5.7 0.19__________________________________________________________________________ denotes values out of the range of the invention
TABLE 7-3__________________________________________________________________________R--Fe--B Magnetic property ofalloy ingots Manufacturing conditions of R--Fe--B magnet alloy Presence of bonded magnetsComparative regenerative magnetic field Br iHc BH.sub.max Squarnesspowders material Hydrogenation Dehydrogenation upon molding (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________103 Temperature: 850.degree. C. Temperature: 850.degree. C. Present 5.7 8.5 6.5 0.24 H.sub.2 pressure: 760 Vacuum: 1 .times. 10.sup.-5 Torr Absent 5.6 8.7 6.2 0.21 104 Present 5.7 9.5 5.7 0.16 Absent 5.6 9.6 5.6 0.15 105 Present 5.5 8.7 6.1 0.22 Absent 5.5 8.7 6.0 0.22 106 Present 5.6 8.9 5.6 0.18 Absent 5.6 9.1 5.5 0.16__________________________________________________________________________ denotes values out of the range of the invention
TABLE 8__________________________________________________________________________ Manufacturing conditions of R--Fe--B magnet alloy Magnetic property Hydrogenation Dehydrogenation of bonded magnets Regenerative Temperature H.sub.2 pressure Temperature Vacuum Br iHc BH.sub.max material (.degree.C.) (Torr) (.degree.C.) (Torr) (KG) (KOe) (MGOe) Hk/iHc__________________________________________________________________________Powders of Stainlessthe invention steel107 plate 750 1 750 5 .times. 10.sup.-4 6.0 9.8 7.2 0.24108 800 1 800 5 .times. 10.sup.-5 6.3 14.5 8.6 0.28109 830 1 830 5 .times. 10.sup.-5 6.3 14.2 8.6 0.27110 870 1 870 1 .times. 10.sup.-5 6.2 13.6 8.2 0.25111 900 1 900 2 .times. 10.sup.-5 6.1 11.3 8.0 0.28112 950 1 950 1 .times. 10.sup.-5 6.1 10.6 8.0 0.29Comparativepowders107 700 1 700 5 .times. 10.sup.-4 5.7 4.3 5.1 0.30108 1000 1 1000 1 .times. 10.sup.-5 3.8 1.2 <1 --__________________________________________________________________________ denotes values out of the range of the invention
TABLE 9______________________________________R-- Fe--Balloy Alloy composition (Atomic %)ingots Nd B Ga Zr Hf Co Fe & impurities______________________________________113 12.5 6.2 -- -- -- 15.3 other114 12.5 6.1 0.5 -- -- 11.2 other115 12.5 6.0 -- 0.2 -- 12.0 other116 12.5 6.0 -- -- 0.2 11.5 other117 12.4 6.2 -- -- -- -- other118 12.4 6.0 0.6 -- -- -- other119 12.4 5.9 -- 0.1 -- -- other120 12.5 6.0 -- -- 0.1 -- other121 12.0 5.9 1.0 0.2 -- 14.0 other122 12.0 5.9 1.0 -- 0.2 14.0 other123 12.1 5.9 1.0 0.2 0.2 14.0 other124 12.9 5.9 0.6 0.1 -- -- other125 13.1 5.9 0.6 -- 0.1 -- other126 13.1 6.0 0.6 0.1 0.1 -- other127 12.4 6.0 -- 0.1 0.2 15.7 other128 12.3 6.1 -- 0.1 0.2 -- other______________________________________
TABLE 10-1__________________________________________________________________________R--Fe--B Manufacturing condition of R--Fe--B magnet alloy Magnetic propertyalloy ingots Use of Hydrogenation Dehydrogenation Presence of of bonded magnetsPowders of regenerative Temperature H.sub.2 pressure Temperature Vacuum magnetic field Br iHc BH.sub.maxthe invention material (.degree.C.) (Torr) (.degree.C.) (Torr) upon molding (KG) (KOe) (MGOe)__________________________________________________________________________113 Used 850 760 850 1 .times. 10.sup.-5 Present 6.8 11.6 9.8 Absent 6.1 11.8 8.1114 Present 8.5 14.2 16.7 Absent 5.8 14.4 7.5115 Present 7.8 10.3 12.1 Absent 5.7 10.3 7.1116 Present 8.1 9.8 15.0 Absent 5.7 10.0 7.2117 Present 6.7 11.0 9.7 Absent 5.9 11.3 7.7118 Present 8.1 14.3 15.1 Absent 5.7 14.5 7.2119 Present 7.5 10.5 12.6 Absent 5.6 10.5 7.3120 Present 7.8 10.0 13.8 Absent 5.6 10.2 7.3__________________________________________________________________________
TABLE 10-2__________________________________________________________________________R-- Fe--B Manufacturing condition of R--Fe--B magnet alloy Magnetic propertyalloy ingots Use of Hydrogenation Dehydrogenation Presence of of bonded magnetsPowders of regenerative Temperature H.sub.2 pressure Temperature Vacuum magnetic field Br iHc BH.sub.maxthe invention material (.degree.C.) (Torr) (.degree.C.) (Torr) upon molding (KG) (KOe) (MGOe)__________________________________________________________________________121 Used 850 760 850 1 .times. 10.sup.-5 Present 7.8 12.1 14.1 Absent 6.1 12.5 8.1122 Present 8.3 10.4 16.0 Absent 6.0 10.8 7.9123 Present 7.8 10.4 13.5 Absent 5.9 10.6 7.5124 Present 7.8 14.8 13.2 Absent 5.9 15.3 7.9125 Present 8.0 12.6 13.5 Absent 5.7 12.9 7.6126 Present 7.8 12.4 13.0 Absent 5.7 12.7 7.5127 Present 8.2 9.6 12.6 Absent 5.6 9.9 7.0128 Present 7.8 8.7 12.0 Absent 5.5 9.2 6.4__________________________________________________________________________
TABLE 11-1__________________________________________________________________________R-- Fe--B Manufacturing condition of R--Fe--B magnet alloy Magnetic propertyalloy ingots Use of Hydrogenation Dehydrogenation Presence of of bonded magnetsComparative regenerative Temperature H.sub.2 pressure Temperature Vacuum magnetic field Br iHc BH.sub.maxpowders material (.degree.C.) (Torr) (.degree.C.) (Torr) upon molding (KG) (KOe) (MGOe)__________________________________________________________________________113 Not Used 850 760 850 1 .times. 10.sup.-5 Present 6.3 9.4 8.1 Absent 5.9 9.5 7.0114 Present 7.6 11.5 11.5 Absent 5.6 11.4 6.3115 Present 7.2 8.4 10.5 Absent 5.5 8.5 6.2116 Present 7.4 7.6 11.2 Absent 5.5 7.8 6.1117 Present 6.1 9.4 8.0 Absent 5.6 9.5 6.6118 Present 7.5 10.8 11.0 Absent 5.5 11.0 6.4119 Present 7.0 9.0 10.0 Absent 5.4 9.1 5.8120 Present 7.2 7.8 10.1 Absent 5.4 8.2 5.5__________________________________________________________________________
TABLE 11-2__________________________________________________________________________R-- Fe--B Manufacturing condition of R--Fe--B magnet alloy Magnetic propertyalloy ingots Use of Hydrogenation Dehydrogenation Presence of of bonded magnetsComparative regenerative Temperature H.sub.2 pressure Temperature Vacuum magnetic field Br iHc BH.sub.maxpowders material (.degree.C.) (Torr) (.degree.C.) (Torr) upon molding (KG) (KOe) (MGOe)__________________________________________________________________________121 Not Used 850 760 850 1 .times. 10.sup.-5 Present 7.3 10.7 11.2 Absent 5.8 10.9 6.4122 Present 7.2 9.0 10.4 Absent 5.8 9.2 6.1123 Present 7.0 9.5 10.5 Absent 5.8 9.4 6.1124 Present 6.5 12.1 9.2 Absent 5.9 12.4 7.0125 Present 6.9 9.3 10.4 Absent 5.9 9.5 6.7126 Present 6.8 10.0 9.9 Absent 5.8 10.4 7.1127 Present 7.0 7.6 9.8 Absent 5.2 7.8 5.0128 Present 7.2 5.4 8.0 Absent 5.0 6.0 4.8__________________________________________________________________________
TABLE 12__________________________________________________________________________ Manufacturing doncitions of R-- Fe--B magnet alloy Magnetic property Hydrogenation Dehydrogenation Molding conditions of bonded magnets Pegenerative Temperature H.sub.2 pressure Temperature Vacuum in the presence of Br iHc BH.sub.max material (.degree.C.) (Torr) (.degree.C.) (Torr) magnetic field (KG) (KOe) (MGOe)__________________________________________________________________________Powders ofthe invention129 Magnesia 750 1 750 2 .times. 10.sup.-4 Magnetic field: 7.8 11.8 12.6130 plate 800 1 800 5 .times. 10.sup.-5 20KOe 8.5 13.6 16.2131 830 1 830 3 .times. 10.sup.-5 Pressure: 8.7 12.4 18.0132 870 1 870 1 .times. 10.sup.-5 6Ton/cm.sup.2 8.6 13.6 17.1133 900 1 900 2 .times. 10.sup.-5 7.8 11.0 13.3134 950 1 950 1 .times. 10.sup.-5 7.8 11.0 13.3Comparativepowders129 700 1 700 4 .times. 10.sup.-4 6.2 10.3 8.4130 1000 1 1000 5 .times. 10.sup.-6 7.4 4.1 6.3__________________________________________________________________________ denotes values out of the range of the invention

Number	Date	Country
1-198836	Jul 1989	JPX
1-198837	Jul 1989	JPX
1-284293	Oct 1989	JPX
2-122651	May 1990	JPX
2-184779	Jul 1990	JPX
2-185951	Jul 1990	JPX

Number	Name	Date	Kind
4935075	Mizoguchi et al.	Jun 1990
4981532	Takeshita et al.	Jan 1991

Number	Date	Country
0274034	Jul 1988	EPX
0304054	Feb 1989	EPX
2303697	Dec 1973	DEX
2387500	Nov 1978	FRX
62-132304	Jun 1987	JPX
1-99201	Apr 1989	JPX
1438091	Mar 1976	GBX
1554384	Oct 1979	GBX

Rare earth permanent magnet powder, method for producing same and bonded magnet

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