Low boron amorphous alloy having excellent soft magnetic characteristics

Abstract

A low boron amorphous alloy having excellent soft magnetic characteristics, composed of B: about 6-10 at %, Si: about 10-17 at %, P: about 0.02-2 at % and the balance Fe and incidental impurities. The invention lowers production costs because the content of expensive boron is reduced.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a low boron amorphous alloy having excellent soft magnetic characteristics, and more specifically to a low boron amorphous alloy in which the boron content is advantageously reduced without deteriorating the magnetic characteristics of the alloy.

2. Description of the Related Art

Various Fe-Si-B alloy compositions are known to possess excellent soft magnetic characteristics.

For example, U.S. Pat. No. 3,856,513 discloses an amorphous alloy containing at least 80 at % Fe, at least 10 at % B and no more than 6 at % Si. Further, U.S. Pat. No. 235,064 discloses an amorphous alloy composed of 77-80 at % Fe, 12-16 at % B and 5-10 at % Si.

Almost all known Fe-Si-B amorphous alloys contain at least 10 at % B, as B is very important to the amorphous property of such alloys. The higher the B content, the stronger the amorphous forming capability of the alloys, whereby thermal stability is improved. Thus, it has been conventionally believed that a B content of at least 10 at % is required to produce excellent soft magnetic characteristics in Fe-Si-B amorphous alloys.

Further, both iron loss and magnetic flux density of conventional Fe-Si-B amorphous alloys containing less than 10 at % B are inferior to alloys containing at least 10 at % B.

Because of the high cost of B, there have been attempts to improve Fe-Si-B amorphous alloys containing less than 10 at % B. For example, C has been added to stabilize age deterioration and to improve amorphous property forming capabilities (Japanese Patent Unexamined Publication No. 57-145964 (1982) and Japanese Patent Unexamined Publication No. 58-42751 (1983)), Mn has been added to improve surface treatment properties (Japanese Patent Unexamined Publication No. 61-136660 (1986), and Cr has been added to improve casting properties (Japanese Patent Unexamined Publication No. 58-210154 (1983)). However, maintaining excellent soft magnetic characteristics in Fe-Si-B alloys containing less than 10 at % B has not been accomplished in the art.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a low boron amorphous alloy having excellent soft magnetic characteristics.

Our investigations led to the discovery that the addition of a small amount of P (0.02-2 at %)accomplishes the above-described described object. More specifically, we discovered that this small addition of P greatly improves the surface roughness of a cast alloy, thereby maintaining excellent soft magnetic characteristics even at a B content below that of conventional amorphous alloys.

That is, the present invention relates to a low boron amorphous alloy having excellent soft magnetic characteristics and having the following composition:

B: about 6-10 at %; Si: about 10-17 at %; P: about 0.02-2 at %; and the balance Fe and incidental impurities. Accordingly it is important that the balance shall consist essentially of Fe and incidental impurities, and that the alloy of this invention shall consist essentially of the above atomic percentage of B, Si and P.

Further, the present invention relates to a low boron amorphous alloy having excellent soft magnetic characteristics and having the following composition:

B: about 6-10 at %; Si: about 10-17 at %; P: about 0.02-2 at %; C: about 0.1-2 at %; and the balance Fe and incidental impurities. Accordingly it is important that the balance shall consist essentially of Fe and incidental impurities, and that the alloy of this invention shall consist essentially of the above atomic percentage of B, Si, P and C.

When low boron amorphous alloys according to the invention are cast into sheets by a single roll method or other conventional technique, the surface roughness of the cast sheet is reduced to where the mean centerline surface roughness Ra on the casting mold side is 0.8 .mu.m or less.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the relationship between B and P contents and surface roughness in a Fe-Si-B amorphous alloy; and

FIG. 2 is a graph showing the relationship between P content and iron loss in Fe-Si-B amorphous alloys having three different B contents.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the results of an investigation into the effect of alloy composition on casting mold side surface roughness of cast alloys. This investigation was conducted on alloys comprising 78 at % Fe, and various quantities of Si, P and B. The alloys were made amorphous by conventional immediate-cooling techniques, such as the single roll method.

As seen in FIG. 1, the addition of P provides improved surface roughness at reduced B contents.

That is, an excellent mean centerline roughness of Ra .ltoreq.0.8 .mu.m is obtained when P content is about 0.02-2 at % and B content is about 6-10 at %.

When alloys having compositions as described above are made amorphous using a conventional immediate-cooling device such as a single roll or the like, the surface roughness of resulting cast alloys can be limited to about 0.8 .mu.m in terms of mean centerline roughness Ra on the casting mold side, whereby magnetic characteristics are improved.

It is preferable that the surface roughness Ra be about 0.6 .mu.m or less to obtain even better magnetic characteristics.

FIG. 2 shows the results of an investigation into the relationship between P content and iron loss with respect to alloy sheets having the following compositions: Fe.sub.78 Si.sub.9-a B.sub.13 P.sub.a (comparative example having a large B content), Fe.sub.78 Si.sub.14-a B.sub.8 P.sub.a (example of the invention) and Fe.sub.78 Si.sub.16.5-a B.sub.5.5 P.sub.a (comparative example having a small B content). As shown in FIG. 2, when B content is about 8 at %, excellent iron loss characteristics are obtained over a P content range of about 0.02-2 at %.

Although the thickness of the alloy sheet is not particularly limited, if cast too thin, surface roughness deteriorates and magnetic flux density decreases. If cast too thick, the rate of cooling is insufficient and iron loss deteriorates. Thus, it is preferable that the sheet thickness be about 17-25 .mu.m so that such problems are eliminated.

A description will be given below of suitable contents for the elements comprising the amorphous alloy of the invention.

B: about 6-10 at %

The upper limit of B content in the invention is about 10 at %. If the B content exceeds about 10 at %, the surface roughness of the alloy sheet increases whereby soft magnetic characteristics deteriorate. Further, production costs soar due to the large quantity of expensive ferroboron used.

The lower B content limit is about 6 at %, as making an amorphous alloy becomes difficult when the B content is below about 6 at %.

A B content of about 7.5-9.5 at % is preferred when the cooling capacity limits of industrial production machines and material costs are taken into account.

Si: about 10-17 at %

Si contributes to reduced magnetostriction and to improved thermal stability of the cast alloy. When Si content is less than about 10 at %, the reduction of magnetostriction is insufficient, whereas when Si content exceeds about 17 at %, sheet brittleness becomes a problem. Thus, Si content is limited to about 10-17 at %.

P: about 0.02-2 at %

In this invention, P is a particularly important element as it is indispensable to the realization of excellent surface roughness and soft magnetic characteristics. When P content is below about 0.02 at %, surface roughness fails to improve sufficiently, whereas when P content exceeds about 2 at %, sheet brittleness increases and thermal stability declines. Thus, P content is limited to a range of about 0.02-2 at %.

In a wide sheet which requires strict brittleness control and excellent thermal stability, it is preferable that P content be about 0.02-0.5 at %.

C: about 0.1-2 at %

C improves soft magnetic characteristics and stabilizes the yield of B when P is added. However, when C content is less than about 0.1 at %, these beneficial effects are not sufficiently realized, whereas when C content exceeds about 2 at %, thermal stability of the sheet is reduced. Thus, C is contained in a range of about 0.1-2 at %.

To maintain product stability in commercial production, it is preferable that C content be within a range of about 0.1-1 at %.

The invention will now be described through illustrative examples. The examples are not intended to limit the scope of the invention defined in the solicited claims.

Various molten alloys having the compositions shown in Table 1 were cast onto the surface a cooling roll (roll diameter: 280 mm) rotating at a peripheral speed of 27 m/sec, thereby producing amorphous alloy sheets.

The following characteristics were evaluated on each amorphous alloy sheet: roughness on the casting mold side, iron loss, magnetic flux density and sheet thickness. The results of the evaluations are shown in Table 1.

As revealed in Table 1, when B content was 10 at % or less (below conventional B content) and P was added in accordance with the present invention, excellent soft magnetic characteristics (comparing favorably to those of conventional alloys having large B contents) were obtained.

According to the present invention, a low boron amorphous alloy having soft magnetic characteristics of the same quality as high boron amorphous alloys can be obtained. Consequently, the invention requires less B, thereby sharply reducing production costs.

Although this invention has been described in connection with specific forms thereof, it will be appreciated that equivalents may be substituted for the specific elements described herein without departing from the spirit and scope of the invention as defined in the appended claims.

TABLE 1__________________________________________________________________________(1) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________1 Fe.sub.78 Si.sub.9 B.sub.13 1.0 0.100 1.530 25 Conventional Example2 Fe.sub.78 Si.sub.13.9 B.sub.8 P.sub.0.1 0.25 0.101 1.521 23 Example of the Inventionh3 Fe.sub.78 Si.sub.12.9 B.sub.9 P.sub.0.1 0.36 0.095 1.532 24 Example of the Invention4 Fe.sub.78 Si.sub.13.4 B.sub.8.5 P.sub.0.1 0.32 0.103 1.524 22 Example of the Invention5 Fe.sub.78 Si.sub.14.4 B.sub.9.5 P.sub.0.1 0.36 0.095 1.509 23 Example of the Invention6 Fe.sub.78 Si.sub.11.9 B.sub.9 P.sub.0.1 C.sub.1 0.38 0.095 1.532 24 Example of the Invention7 Fe.sub.78 Si.sub.9.9 B.sub.9 P.sub.0.1 C.sub.1 0.28 0.105 1.540 23 Example of the Invention8 Fe.sub.78 Si.sub.16.4 B.sub.5.5 P.sub.0.1 1.50 2.305 0.985 24 Comparative Example9 Fe.sub.78 Si.sub.10.9 B.sub.12 P.sub.0.1 0.95 0.121 1.505 25 Comparative Example10 Fe.sub.78 Si.sub.8.9 B.sub.13 P.sub.0.1 0.92 0.132 1.506 26 Comparative Example11 Fe.sub.78 Si.sub.13.5 B.sub.8.5 1.05 0.195 1.479 23 Comparative Example12 Fe.sub.78 Si.sub.12.5 B.sub.9.5 0.93 0.184 1.482 25 Comparative Example13 Fe.sub.78 Si.sub.13.98 B.sub.8 P.sub.0.02 0.61 0.101 1.500 18 Example of the Invention14 Fe.sub.78 Si.sub.13.8 B.sub.8 P.sub.0.2 0.65 0.102 1.505 19 Example of the Invention15 Fe.sub.78 Si.sub.12 B.sub.8 P.sub.2 0.79 0.106 1.500 20 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(2) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________16 Fe.sub.78 Si.sub.12.98 B.sub.8 P.sub.0.02 C.sub.1 0.41 0.102 1.504 20 Example of the Invention17 Fe.sub.78 Si.sub.12.9 B.sub.8 P.sub.0.1 C.sub.1 0.53 0.101 1.505 19 Example of the Invention18 Fe.sub.78 Si.sub.12.8 B.sub.8 P.sub.0.2 C.sub.1 0.54 0.103 1.506 17 Example of the Invention19 Fe.sub.78 Si.sub.11 B.sub.8 P.sub.2 Cl.sub.1 0.69 0.105 1.510 19 Example of the Invention20 Fe.sub.78 Si.sub.12.98 B.sub.9 P.sub.0.02 0.55 0.102 1.512 19 Example of the Invention21 Fe.sub.78 Si.sub.12.8 B.sub.9 P.sub.0.2 0.58 0.098 1.514 18 Example of the Invention22 Fe.sub.78 Si.sub.11 B.sub.9 P.sub.2 0.52 0.096 1.515 18 Example of the Invention23 Fe.sub.78 Si.sub.11.98 B.sub.9 P.sub.0.02 C.sub.1 0.42 0.097 1.520 20 Example of the Invention24 Fe.sub.78 Si.sub.11.8 B.sub.9 P.sub.0.2 C.sub.1 0.51 0.101 1.518 20 Example of the Invention25 Fe.sub.78 Si.sub.11 B.sub.9 P.sub.2 C.sub.1 0.58 0.095 1.515 20 Example of the Invention26 Fe.sub.78 Si.sub.11.98 B.sub.10 P.sub.0.02 0.50 0.094 1.520 19 Example of the Invention27 Fe.sub.78 Si.sub.11.8 B.sub.10 P.sub.0.2 0.51 0.097 1.521 18 Example of the Invention28 Fe.sub.78 Si.sub.10 B.sub.10 P.sub.2 0.53 0.098 1.523 23 Example of the Invention29 Fe.sub.78 Si.sub.10.98 B.sub.10 P.sub.0.02 C.sub.1 0.43 0.095 1.524 19 Example of the Invention30 Fe.sub.78 Si.sub.10.8 B.sub.10 P.sub.0.2 C.sub.1 0.42 0.094 1.520 19 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(3) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________31 Fe.sub.78 Si.sub.9 B.sub.10 P.sub.2 C.sub.1 0.54 0.098 1.518 20 Example of the Invention32 Fe.sub.76 Si.sub.14.98 B.sub.9 P.sub.0.02 0.65 0.110 1.509 19 Example of the Invention33 Fe.sub.76 Si.sub.14.8 B.sub.9 P.sub.0.2 0.64 0.108 1.508 18 Example of the Invention34 Fe.sub.76 Si.sub.13 B.sub.9 P.sub.2 0.62 0.109 1.511 20 Example of the Invention35 Fe.sub.76 Si.sub.13.98 B.sub.9 P.sub.0.02 C.sub.1 0.51 0.109 1.512 19 Example of the Invention36 Fe.sub.76 Si.sub.13.8 B.sub.9 P.sub.0.2 C.sub.1 0.62 0.111 1.509 20 Example of the Invention37 Fe.sub.76 Si.sub.12 B.sub.9 P.sub.2 C.sub.1 0.66 0.105 1.508 21 Example of the Invention38 Fe.sub.76 Si.sub.14.48 B.sub.9.5 P.sub.0.02 0.43 0.080 1.503 18 Example of the Invention39 Fe.sub.76 Si.sub.14.3 B.sub.9.5 P.sub.0.2 0.44 0.078 1.501 18 Example of the Invention40 Fe.sub.76 Si.sub.12.5 B.sub.9.5 P.sub.2 0.57 0.083 1.505 18 Example of the Invention41 Fe.sub.76 Si.sub.13.48 B.sub.9.5 P.sub.0.02 C.sub.1 0.49 0.095 1.503 19 Example of the Invention42 Fe.sub.76 Si.sub.13.3 B.sub.9.5 P.sub.0.2 C.sub.1 0.58 0.093 1.504 21 Example of the Invention43 Fe.sub.76 Si.sub.11.5 B.sub.9.5 P.sub.2 C.sub.1 0.53 0.097 1.505 19 Example of the Invention44 Fe.sub.76 Si.sub.13.98 B.sub.10 P.sub.0.02 0.57 0.105 1.504 19 Example of the Invention45 Fe.sub.76 Si.sub.13.8 B.sub.10 P.sub.0.2 0.53 0.102 1.505 21 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(4) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________46 Fe.sub.76 Si.sub.12 B.sub.10 P.sub.2 0.64 0.099 1.501 20 Example of the Invention47 Fe.sub.76 Si.sub.12.98 B.sub.10 P.sub.0.02 C.sub.1 0.48 0.098 1.503 19 Example of the Invention48 Fe.sub.76 Si.sub.12.8 B.sub.10 P.sub.0.2 C.sub.1 0.42 0.095 1.503 18 Example of the Invention49 Fe.sub.76 Si.sub.11 B.sub.10 P.sub.2 Cl.sub.1 0.51 0.093 1.500 18 Example of the Invention50 Fe.sub.80 Si.sub.11.98 B.sub.8 P.sub.0.02 0.64 0.096 1.345 18 Example of the Invention51 Fe.sub.80 Si.sub.11.8 B.sub.8 P.sub.0.2 0.62 0.095 1.541 20 Example of the Invention52 Fe.sub.80 Si.sub.10 B.sub.8 P.sub.2 0.59 0.102 1.525 20 Example of the Invention53 Fe.sub.80 Si.sub.11.88 B.sub.8 P.sub.0.02 C.sub.0.1 0.55 0.098 1.542 23 Example of the Invention54 Fe.sub.80 Si.sub.11.7 B.sub.8 P.sub.0.2 C.sub.0.1 0.61 0.100 1.540 21 Example of the Invention55 Fe.sub.80 Si.sub.9.9 B.sub.1 P.sub.2 C.sub.0.1 0.55 0.102 1.523 20 Example of the Invention56 Fe.sub.80 Si.sub.9.98 B.sub.8 P.sub.0.02 C.sub.2 0.49 0.096 1.541 19 Example of the Invention57 Fe.sub.80 Si.sub.9.8 B.sub.8 P.sub.0.2 C.sub.2 0.50 0.098 1.538 19 Example of the Invention58 Fe.sub.80 Si.sub.8 B.sub.8 P.sub.2 C.sub.2 0.51 0.104 1.526 18 Example of the Invention59 Fe.sub.80 Si.sub.10.98 B.sub.9 P.sub.0.02 0.63 0.092 1.542 21 Example of the Invention60 Fe.sub.80 Si.sub.10.8 B.sub.9 P.sub.0.2 0.61 0.094 1.543 19 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(5) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________61 Fe.sub.80 Si.sub.9 B.sub.9 P.sub.2 0.69 0.103 1.522 22 Example of the Invention62 Fe.sub.80 Si.sub.10.88 B.sub.9 P.sub.0.02 C.sub.0.1 0.55 0.094 1.545 23 Example of the Invention63 Fe.sub.80 Si.sub.10.7 B.sub.9 P.sub.0.2 C.sub.0.1 0.60 0.099 1.541 23 Example of the Invention64 Fe.sub.80 Si.sub.8.9 B.sub.9 P.sub.2 C.sub.0.1 0.62 0.102 1.524 22 Example of the Invention65 Fe.sub.80 Si.sub.8.98 B.sub.9 P.sub.0.02 C.sub.2 0.50 0.095 1.546 22 Example of the Invention66 Fe.sub.80 Si.sub.8.8 B.sub.9 P.sub.0.2 C.sub.2 0.48 0.096 1.542 21 Example of the Invention67 Fe.sub.80 Si.sub.7 B.sub.9 P.sub.2 C.sub.2 0.65 0.101 1.521 18 Example of the Invention68 Fe.sub.80 Si.sub.9.98 B.sub.10 P.sub.0.02 0.64 0.088 1.541 19 Example of the Invention69 Fe.sub.80 Si.sub.9.8 B.sub.10 P.sub.0.2 0.69 0.087 1.540 23 Example of the Invention70 Fe.sub.80 Si.sub.8 B.sub.10 P.sub.2 0.72 0.099 1.523 19 Example of the Invention71 Fe.sub.80 Si.sub.9.88 B.sub.10 P.sub.0.02 C.sub.0.1 0.68 0.089 1.545 18 Example of the Invention72 Fe.sub.80 Si.sub.9.7 B.sub.10 P.sub.0.2 C.sub.0.1 0.61 0.087 1.546 22 Example of the Invention73 Fe.sub.80 Si.sub.7.9 B.sub.10 P.sub.2 C.sub.0.1 0.57 0.100 1.522 20 Example of the Invention74 Fe.sub.80 Si.sub.7.98 B.sub.10 P.sub.0.02 C.sub.2 0.49 0.094 1.545 21 Example of the Invention75 Fe.sub.80 Si.sub.7.8 B.sub.10 P.sub.0.2 C.sub.2 0.48 0.095 1.547 21 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(6) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________76 Fe.sub.80 Si.sub.6 B.sub.10 P.sub.2 C.sub.2 0.55 0.102 1.526 22 Example of the Invention77 Fe.sub.78 Si.sub.13.88 B.sub.8 P.sub.0.02 C.sub.0.1 0.59 0.094 1.535 19 Example of the Invention78 Fe.sub.78 Si.sub.13.7 B.sub.8 P.sub.0.2 C.sub.0.1 0.68 0.098 1.532 23 Example of the Invention79 Fe.sub.78 Si.sub.11.9 B.sub.8 P.sub.2 C.sub.0.1 0.72 0.100 1.515 18 Example of the Invention80 Fe.sub.78 Si.sub.1.98 B.sub.8 P.sub.0.02 C.sub.2 0.75 0.092 1.534 19 Example of the Invention81 Fe.sub.78 Si.sub.11.8 B.sub.8 P.sub.0.2 C.sub.2 0.71 0.091 1.532 20 Example of the Invention82 Fe.sub.78 Si.sub.10 B.sub.8 P.sub.2 C.sub.2 0.69 0.102 1.516 18 Example of the Invention83 Fe.sub.78 Si.sub.12.88 B.sub.9 P.sub.0.02 C.sub.0.1 0.51 0.096 1.536 18 Example of the Invention84 Fe.sub.78 Si.sub.12.7 B.sub.9 P.sub.0.2 C.sub.0.1 0.57 0 .094 1.532 22 Example of the Invention85 Fe.sub.78 Si.sub.10.9 B.sub.9 P.sub.2 C.sub.0.1 0.59 0.101 1.518 23 Example of the Invention86 Fe.sub.78 Si.sub.10.98 B.sub.9 P.sub.0.02 C.sub.2 0.57 0.095 1.538 18 Example of the Invention87 Fe.sub.78 Si.sub.10.8 B.sub.9 P.sub.0.2 C.sub.2 0.58 0.093 1.532 19 Example of the Invention88 Fe.sub.78 Si.sub.9 B.sub.9 P.sub.2 C.sub.2 0.58 0.103 1.513 23 Example of the Invention89 Fe.sub.78 Si.sub.11.88 B.sub.10 P.sub.0.02 C.sub.0.1 0.65 0 .093 1.536 21 Example of the Invention90 Fe.sub.78 Si.sub.11.7 B.sub.10 P.sub.0.2 C.sub.0.1 0.67 0.094 1.531 20 Example of the Invention__________________________________________________________________________ TABLE 1__________________________________________________________________________(7) Iron Magnetic Surface Loss Flux ThicknessSpecimen Composition Roughness W.sub.13/50 Density of SheetNo. (at %) Ra (.mu.m) (W/kg) B.sub.8 (T) (.mu.m) Reference__________________________________________________________________________91 Fe.sub.78 Si.sub.9.9 B.sub.10 P.sub.2 C.sub.0.1 0.70 0.100 1.514 21 Example of the Invention92 Fe.sub.78 Si.sub.9.98 B.sub.10 P.sub.0.02 C.sub.2 0.52 0.092 1.538 23 Example of the Invention93 Fe.sub.78 Si.sub.9.8 B.sub.10 P.sub.0.2 C.sub.2 0.54 0.093 1.534 22 Example of the Invention94 Fe.sub.78 Si.sub.8 B.sub.10 P.sub.2 C.sub.2 0.55 0.101 1.513 23 Example of the Invention95 Fe.sub.76 Si.sub.14.38 B.sub.9.5 P.sub.0.02 C.sub.0.1 0.64 0.078 1.520 20 Example of the Invention96 Fe.sub.76 Si.sub.14.2 B.sub.9.5 P.sub.0.2 C.sub.0.1 0.63 0.082 1.515 18 Example of the Invention97 Fe.sub.76 Si.sub.12.4 B.sub.9.5 P.sub.2 C.sub.0.1 0.70 0.088 1.490 18 Example of the Invention98 Fe.sub.76 Si.sub.12.48 B.sub.9.5 P.sub.0.02 C.sub.2 0.55 0.075 1.521 19 Example of the Invention99 Fe.sub.76 Si.sub.12.3 B.sub.9.5 P.sub.0.2 C.sub.2 0.54 0.076 1.518 22 Example of the Invention100 Fe.sub.76 Si.sub.10.5 B.sub.9.5 P.sub.2 C.sub.2 0.59 0.079 1.491 21 Example of the Invention__________________________________________________________________________

Claims

1. A low boron amorphous alloy having excellent soft magnetic characteristics, consisting of:

about 6-10 at % B;

about 10-17 at % Si;

about 0.02-2 at % P; and

the balance Fe and incidental impurities.

2. A low boron amorphous alloy having excellent soft magnetic characteristics, consisting of:

about 6-10 at % B;

about 10-17 at % Si;

about 0.02-2 at % P;

about 0.1-2 at % C; and

the balance Fe and incidental impurities.

3. A low boron amorphous alloy cast sheet having excellent soft magnetic characteristics and having an alloy composition according to claim 1, wherein said cast sheet has a mean centerline surface roughness Ra on the casting mold side of about 0.8 .mu.m or less.

4. A low boron amorphous alloy cast sheet having excellent soft magnetic characteristics and having an alloy composition according to claim 2, wherein said cast sheet has a mean centerline surface roughness Ra on the casting mold side of about 0.8 .mu.m or less.