The disclosure is directed to Fe—Ni—P—B—Ge alloys capable of forming bulk metallic glass rods with diameters greater than 1 mm and up to 4 mm or larger.
Metal alloys which are most easily obtained in the amorphous state by rapid quenching from the melt state are mixtures of transition metals with metalloids, i.e. semimetals. U.S. Pat. No. 4,144,058 by Chen et al discloses iron (Fe)-nickel (Ni) alloys bearing phosphorus (P) and boron (B) having compositions that vary over a very broad range capable of forming metallic glasses in the form of sheets, ribbons, or powders with lateral dimensions on the order of tens of micrometers. Chen et al mentions that additions of aluminum (Al), silicon (Si), tin (Sn), antimony (Sb), indium (In), Beryllium (Be), as well as germanium (Ge) within the range of up to 15 atomic percent were found to form such micrometer thick sheets, ribbons or powders. However, Chen et al provides no example of an Fe—Ni—P—B—Ge alloy.
Generally, there may be a small range of compositions surrounding each of the known metallic glass forming compositions where the amorphous state can be obtained in bulk form by rapid quenching from the melt state, that is, to be formed in millimeter size objects rather than micrometer size objects. No practical guidelines are known for predicting with certainty the precise compositional ranges that will encompass bulk metallic glass forming alloys that are “significantly better” glass formers than the marginal glass formers generally found over much broader compositional ranges (e.g. those disclosed by Chen et al). In fact, no practical guideline is known for predicting whether such a narrow range of bulk metallic glass forming alloys will even exist within the very broad range of marginal metallic glass forming alloys.
Due to the attractive engineering properties of Fe-Ni based P and B bearing bulk glasses, such as high strength, high toughness, bending ductility, and corrosion resistance, there remains a need to develop alloys with comparable engineering performance but with significantly improved glass-forming ability such that bulk engineering components can be produced.
In the present disclosure, Fe—Ni—P—B—Ge alloys and metallic glasses are disclosed. Metallic glass rods with diameters up to several millimeters can be formed from the disclosed alloys. The identity of this narrow composition range or even its existence has not been previously disclosed. In various embodiments, Fe—Ni—P—B—Ge alloys containing Ge in concentrations ranging from 2 atomic percent to 6 atomic percent, and demonstrate significantly better glass forming ability than Fe—Ni—P—B alloys that are free of Ge.
In one embodiment, the disclosure is directed to a metallic glass or an alloy represented by the following formula (a, b, and c subscripts denote atomic percent; y subscript denotes atomic fraction) in Equation (1):
[Fe1-yNiy](100-a-b-c)PaBbGec Eq.(1)
where:
an atomic percent of P a is between 9 and 12, an atomic percent of B b is between 5.5 and 7.5, an atomic percent of Ge c is between 2 and 6, and an atomic fraction y is between 0.45 and 0.55. Metallic glass rods having a diameter of at least 1 mm can be formed by rapid quenching such metallic glasses from the molten state.
In another embodiment, a+b+c is between 21 and 23, and wherein metallic glass rods having a diameter of at least 2 mm can be formed by rapid quenching such metallic glasses from the molten state.
In yet another embodiment, y is between 0.475 and 0.525, and wherein metallic glass rods having a diameter of at least 2 mm can be formed by rapid quenching such metallic glasses from the molten state.
In yet another embodiment, a is between 10 and 11.5, and wherein metallic glass rods having a diameter of at least 2 mm can be formed by rapid quenching such metallic glasses from the molten state.
In yet another embodiment, b is between 6 and 7, and wherein metallic glass rods having a diameter of at least 2 mm can be formed by rapid quenching such metallic glasses from the molten state.
In yet another embodiment, c is between 4 and 5.5, and wherein metallic glass rods having a diameter of at least 2 mm can be formed by rapid quenching such metallic glasses from the molten state.
In yet another embodiment, up to 5 atomic percent of Fe, Ni, or both is substituted by Co.
In yet another embodiment, up to 2.5 atomic percent of Ni, Fe, or both is substituted by Cr, Ru, Pd, or combinations thereof.
In yet another embodiment, up to 2.5 atomic percent of P, Ge, or both is substituted by Sn, Si, Sb, or combinations thereof.
In yet another embodiment, up to 2.5 atomic percent of B is substituted by C.
In yet another embodiment, the melt is fluxed with a reducing agent prior to rapid quenching.
In yet another embodiment, the reducing agent is boron oxide (B2O3).
In yet another embodiment, the temperature of the melt prior to quenching is at least 100 degrees above the liquidus temperature of the alloy.
In yet another embodiment, the temperature of the melt prior to quenching is at least 1100° C.
In yet another embodiment, a bulk ferromagnetic core can be formed from the alloys and used in a product selected from the group consisting of inductors, transformers, clutches, and DC/AC converters.
In some embodiments, the disclosure is also directed to metallic glass compositions or alloy compositions Fe39Ni39P11B6.6Ge4.4, Fe38.9Ni39.1P11B6.6Ge4.4, Fe38.8Ni39.2P11B6.6Ge4.4, Fe38.7Ni39.3P11B6.6Ge4.4, Fe38.6Ni39.4P11B6.6Ge4.4, Fe38.7Ni39.3P11.2B6.6Ge4.2, Fe38.7Ni39.3P10.8B6.6Ge4.6, Fe38.7Ni39.3P10.4B6.6Ge5, Fe38.7Ni39.3P10.3B6.6Ge5.1, Fe38.7Ni39.3P10.6B6.6Ge5.4, Fe38.7Ni39.3P10.3B6.7Ge5, Fe38.7Ni39.3P10.5B6.5Ge5, Fe38.8Ni39.4P10.2B6.7Ge5, and Fe38.6Ni39.2P10.6B6.7Ge5,
The disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as described below. It is noted that, for purposes of illustrative clarity, certain elements in various drawings may not be drawn to scale.
In accordance with the provided disclosure and drawings, Fe—Ni—P—B—Ge alloys are provided within a well-defined composition range. These alloys can form metallic glass rods with diameters greater than at least 1 mm. Specifically, by controlling the relative concentrations of Ge to be from 2 to 6 atomic percent, the amorphous phase of these alloys can be formed into metallic glass rods with diameters greater than at least 1 mm.
The disclosure provides alloys that have a good glass forming ability. The Fe—Ni—P—B—Ge alloys capable of forming metallic glasses rods with diameters of up to 4 mm or larger have significantly better glass forming ability than the metallic glasses disclosed in U.S. Pat. No. 4,144,058 by Chen et al, which were capable of forming metallic wires with diameters of only about 100 micrometers.
In the present disclosure, the glass-forming ability of each alloy is quantified by the “critical rod diameter”, defined as maximum rod diameter in which the amorphous phase can be formed when processed by a method of water quenching a quartz tube with 0.5 m thick walls containing a molten alloy.
In some aspects, the “critical cooling rate” defined as the cooling rate required to avoid crystallization and form the amorphous phase of the alloy (i.e. the metallic glass) depends on the composition of the alloys. The lower the critical cooling rate of an alloy, the larger its critical rod diameter would be. The critical cooling rate Rc in K/s and critical rod diameter dc in mm are known in the art to be related via the following empirical Equation:
R
c=1000/dc2 Eq.(2)
According to Eq. (2), the critical cooling rate for an alloy having a critical rod diameter of about 0.1 mm, such as the one disclosed by Chen et al., is about 100,000 K/s. On the other hand, the critical cooling rate for an alloy having a critical rod diameter of about 4 mm, as in the case of the alloys according to embodiments of the present disclosure, is only about 60 K/s. Therefore, forming the metallic glass phase from the alloys according to the present disclosure requires cooling rates that are more than three orders of magnitude lower than the alloys of the Chen et al. disclosure. This suggests that the alloys according to the present disclosure unexpectedly demonstrate a glass forming ability that is considerably better than the alloys according to the Chen et al. patent.
Specific embodiments of Fe—Ni—P—B—Ge alloys and metallic glasses demonstrating the effect on glass forming ability of increasing the Ni atomic concentration by substituting Fe according to the formula Fe39−xNi39+xP11B6.6Ge4.4 are presented in Table 1, and are plotted in
It was also found that when y is between 0.475 and 0.525, metallic glass rods of diameter of at least 2 mm can be formed. It was further found that formation of metallic glass rods having diameters of at least 1 mm is possible over a broader range of an atomic fraction y from about 0.45 to about 0.55.
Differential calorimetry scans corresponding to example metallic glasses listed in Table 2 are presented in
Example metallic glasses demonstrating the effect of substituting P by Ge according to the formula Fe38.7Ni39.3P11.2−xB6.6Ge4.2+x on the glass forming ability of the Fe—Ni—P—B—Ge alloys are presented in Table 2. Example metallic glasses 6-10 have an Fe concentration of 38.7 atomic percent, a Ni concentration of 39.3 atomic percent, a B concentration of 6.6 atomic percent, and varying Ge and P concentrations. The data suggests that bulk metallic glass formation, such as metallic glass rods with diameters greater than 2.5 mm, is possible when c in Eq. (1) ranges between about 4.2 and 5.4, and when a total concentration of P, B, and Ge (a+b+c) is fixed at about 22.
It was found that formation of metallic glass rods with critical rod diameters of at least 1 mm is possible over a broader range of Ge concentration, c, from about 2 to about 6. Alloys with such narrow composition range demonstrate surprisingly higher glass forming ability than alloys with compositions outside this narrow Ge range. For example, the critical rod diameter is much less than 1 mm when c is less than 2 atomic percent or greater than 6 atomic percent. It was also found that when c is between 4 and 5.5, metallic glass rods with diameters of at least 2 mm can be formed by rapid quenching from the molten state.
An image of a 4 mm diameter rod of metallic glass Fe38.7Ni39.3P10.4B6.6Ge5 is presented in
Example metallic glasses demonstrating the effect of substituting P by B according to the formula Fe38.7Ni39.3P19.3+xB6.7+xGe5 on the glass forming ability of the Fe—Ni—P—B—Ge alloys are presented in Table 3, and are plotted in
It was found that formation of metallic glass rods with at least 1 mm diameter is possible over a range of B concentration, b, from about 5.5 to about 7.5. Alloys within such narrow composition range demonstrate surprisingly higher glass forming ability than alloys with compositions outside this range of B. It was also found that when b is between 6 and 7, metallic glass rods of diameter of at least 2 mm can be formed by rapid quenching from the molten state.
Example metallic glasses demonstrating the effect of increasing the P atomic concentration by substituting both Fe and Ni according to the formula Fe38.8−xN39.4−xP10.2+2xB6.6Ge5 on the glass forming ability of the Fe—Ni—P—B—Ge alloys are presented in Table 4, and are plotted in
It was found that when a is between 10 and 11.5, metallic glass rods with diameters of at least 2 mm can be formed by rapid quenching from the molten state. It was also found that formation of metallic glass rods with diameters of at least 1 mm is possible over a broader range of a, from about 9 to about 12. Alloys within such a narrow composition range demonstrate surprisingly higher glass forming ability than alloys with compositions outside the P range of 9 to 12 atomic percent.
The effect of fluxing the alloys with boron oxide (B2O3) prior to rapidly quenching to form the metallic glass rods is also investigated. Fluxing is a chemical process by which the fluxing agent acts to “reduce” the oxides entrained in the glass-forming alloy that could potentially impair glass formation by catalyzing crystallization. Whether fluxing is beneficial in promoting glass formation is determined by the chemistry of the alloy and the fluxing agent. For the chemistry of the alloys described herein, fluxing with B2O3 was determined to dramatically improve bulk-glass formation. All data shown in Tables 1-4, and
As an example, alloy composition Fe38.7Ni39.3P10.4B6.6Ge5 is capable of forming metallic glass rods with diameters of up to 4 mm when fluxed with B2O3. Without fluxing, the alloy was found to be incapable of forming metallic glass rods of at least 1 mm in diameter. The fluxing results are presented in Table 5. As shown, fluxing promotes bulk metallic glass formation.
In some embodiments, up to 5 atomic percent of either Fe or Ni or both is substituted by Co. In some embodiments, up to 2.5 atomic percent of either Ni or Fe or both is substituted by Cr, Ru, Pd, or combinations thereof. In some embodiments, up to 2.5 atomic percent of either P, Ge, or both is substituted by Sn, Si, Sb, or combinations thereof. In some embodiments, up to 2.5 atomic percent of B is substituted by C.
A method for producing the alloyed ingots of the disclosure involves inductive melting of the appropriate amounts of elemental constituents in a quartz tube under inert atmosphere. The purity levels of the constituent elements were as follows: Fe 99.95%, Ni 99.995%, B 99.5%, P 99.9999%, and Ge 99.999%. In some embodiments, the alloyed ingots are fluxed with dehydrated boron oxide (B2O3) by re-melting the ingots in a quartz tube under inert atmosphere, bringing the alloy melt in contact with the boron oxide melt and allowing the two melts to interact for at least 500 s at a temperature of at least 1100° C., and subsequently water quenching.
A method for producing metallic glass rods from the alloys of the disclosure involves re-melting the alloyed ingots in cylindrical quartz tubes with 0.5 mm thick walls in a furnace at temperature between 1150 and 1250° C. under high purity argon and rapidly quenching in a room-temperature water bath.
Optionally, amorphous articles can also be produced from the alloy of the disclosure by re-melting the alloyed ingots in a crucible made of a material that includes, without limitation, quartz, graphite, alumina, and/or zirconia, and injecting or pouring the molten alloy into a metal mold made of a material that includes, without limitation, copper, brass, and/or steel.
Optionally, prior to producing an amorphous article, the alloyed ingots can be fluxed with a reducing agent (e.g. B2O3) by re-melting the ingots in a quartz tube under inert atmosphere, bringing the alloy melt in contact with the molten reducing agent, and allowing the two melts to interact for about 1000 s at a temperature of about 1200° C. or higher, under inert atmosphere and subsequently water quenching.
The glass-forming ability of each alloy was assessed by determining the maximum rod diameter in which the amorphous phase of the alloy (i.e. the metallic glass phase) could be formed when processed by the method described above. X-ray diffraction with Cu-Ka radiation was performed to verify the amorphous structure of the alloys.
Differential scanning calorimetry was performed on sample metallic glasses at a scan rate of 20 K/min to determine the glass-transition, crystallization, solidus, and liquidus temperatures of sample metallic glasses.
Having described several embodiments, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.
Those skilled in the art will appreciate that the presently disclosed embodiments teach by way of example and not by limitation. Therefore, the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.
The application claims priority to U.S. Provisional Patent Application No. 61/725,394, entitled “Bulk Iron-Nickel Glasses Bearing Phosphorus-Boron and Germanium”, filed on Nov. 12, 2012, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61725394 | Nov 2012 | US |