Low boron amorphous alloy having excellent soft magnetic characteristics
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 μm 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 ≦0.8 μm 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 μm 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 μm 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 78  Si 9-a  B 13  P a  (comparative example having a large B content), Fe 78  Si 14-a  B 8  P a  (example of the invention) and Fe 78  Si 16 .5-a B 5 .5 P 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 μm 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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       Reference                          
__________________________________________________________________________
1    Fe.sub.78 Si.sub.9 B.sub.13                                          
                 1.0   0.100                                              
                            1.530                                         
                                 25    Conventional Example               
2    Fe.sub.78 Si.sub.13.9 B.sub.8 P.sub.0.1                              
                 0.25  0.101                                              
                            1.521                                         
                                 23    Example of the Invention           
h3   Fe.sub.78 Si.sub.12.9 B.sub.9 P.sub.0.1                              
                 0.36  0.095                                              
                            1.532                                         
                                 24    Example of the Invention           
4    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 Invention           
5    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 Invention           
6    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 Invention           
7    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 Invention           
8    Fe.sub.78 Si.sub.16.4 B.sub.5.5 P.sub.0.1                            
                 1.50  2.305                                              
                            0.985                                         
                                 24    Comparative Example                
9    Fe.sub.78 Si.sub.10.9 B.sub.12 P.sub.0.1                             
                 0.95  0.121                                              
                            1.505                                         
                                 25    Comparative Example                
10   Fe.sub.78 Si.sub.8.9 B.sub.13 P.sub.0.1                              
                 0.92  0.132                                              
                            1.506                                         
                                 26    Comparative Example                
11   Fe.sub.78 Si.sub.13.5 B.sub.8.5                                      
                 1.05  0.195                                              
                            1.479                                         
                                 23    Comparative Example                
12   Fe.sub.78 Si.sub.12.5 B.sub.9.5                                      
                 0.93  0.184                                              
                            1.482                                         
                                 25    Comparative Example                
13   Fe.sub.78 Si.sub.13.98 B.sub.8 P.sub.0.02                            
                 0.61  0.101                                              
                            1.500                                         
                                 18    Example of the Invention           
14   Fe.sub.78 Si.sub.13.8 B.sub.8 P.sub.0.2                              
                 0.65  0.102                                              
                            1.505                                         
                                 19    Example of the Invention           
15   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       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 Invention           
17   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 Invention           
18   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 Invention           
19   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 Invention           
20   Fe.sub.78 Si.sub.12.98 B.sub.9 P.sub.0.02                            
                 0.55  0.102                                              
                            1.512                                         
                                 19    Example of the Invention           
21   Fe.sub.78 Si.sub.12.8 B.sub.9 P.sub.0.2                              
                 0.58  0.098                                              
                            1.514                                         
                                 18    Example of the Invention           
22   Fe.sub.78 Si.sub.11 B.sub.9 P.sub.2                                  
                 0.52  0.096                                              
                            1.515                                         
                                 18    Example of the Invention           
23   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 Invention           
24   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 Invention           
25   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 Invention           
26   Fe.sub.78 Si.sub.11.98 B.sub.10 P.sub.0.02                           
                 0.50  0.094                                              
                            1.520                                         
                                 19    Example of the Invention           
27   Fe.sub.78 Si.sub.11.8 B.sub.10 P.sub.0.2                             
                 0.51  0.097                                              
                            1.521                                         
                                 18    Example of the Invention           
28   Fe.sub.78 Si.sub.10 B.sub.10 P.sub.2                                 
                 0.53  0.098                                              
                            1.523                                         
                                 23    Example of the Invention           
29   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 Invention           
30   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       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 Invention           
32   Fe.sub.76 Si.sub.14.98 B.sub.9 P.sub.0.02                            
                 0.65  0.110                                              
                            1.509                                         
                                 19    Example of the Invention           
33   Fe.sub.76 Si.sub.14.8 B.sub.9 P.sub.0.2                              
                 0.64  0.108                                              
                            1.508                                         
                                 18    Example of the Invention           
34   Fe.sub.76 Si.sub.13 B.sub.9 P.sub.2                                  
                 0.62  0.109                                              
                            1.511                                         
                                 20    Example of the Invention           
35   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 Invention           
36   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 Invention           
37   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 Invention           
38   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 Invention           
39   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 Invention           
40   Fe.sub.76 Si.sub.12.5 B.sub.9.5 P.sub.2                              
                 0.57  0.083                                              
                            1.505                                         
                                 18    Example of the Invention           
41   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 Invention           
42   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 Invention           
43   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 Invention           
44   Fe.sub.76 Si.sub.13.98 B.sub.10 P.sub.0.02                           
                 0.57  0.105                                              
                            1.504                                         
                                 19    Example of the Invention           
45   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       Reference                          
__________________________________________________________________________
46   Fe.sub.76 Si.sub.12 B.sub.10 P.sub.2                                 
                 0.64  0.099                                              
                            1.501                                         
                                 20    Example of the Invention           
47   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 Invention           
48   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 Invention           
49   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 Invention           
50   Fe.sub.80 Si.sub.11.98 B.sub.8 P.sub.0.02                            
                 0.64  0.096                                              
                            1.345                                         
                                 18    Example of the Invention           
51   Fe.sub.80 Si.sub.11.8 B.sub.8 P.sub.0.2                              
                 0.62  0.095                                              
                            1.541                                         
                                 20    Example of the Invention           
52   Fe.sub.80 Si.sub.10 B.sub.8 P.sub.2                                  
                 0.59  0.102                                              
                            1.525                                         
                                 20    Example of the Invention           
53   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 Invention           
54   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 Invention           
55   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 Invention           
56   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 Invention           
57   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 Invention           
58   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 Invention           
59   Fe.sub.80 Si.sub.10.98 B.sub.9 P.sub.0.02                            
                 0.63  0.092                                              
                            1.542                                         
                                 21    Example of the Invention           
60   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       Reference                          
__________________________________________________________________________
61   Fe.sub.80 Si.sub.9 B.sub.9 P.sub.2                                   
                 0.69  0.103                                              
                            1.522                                         
                                 22    Example of the Invention           
62   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 Invention           
63   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 Invention           
64   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 Invention           
65   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 Invention           
66   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 Invention           
67   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 Invention           
68   Fe.sub.80 Si.sub.9.98 B.sub.10 P.sub.0.02                            
                 0.64  0.088                                              
                            1.541                                         
                                 19    Example of the Invention           
69   Fe.sub.80 Si.sub.9.8 B.sub.10 P.sub.0.2                              
                 0.69  0.087                                              
                            1.540                                         
                                 23    Example of the Invention           
70   Fe.sub.80 Si.sub.8 B.sub.10 P.sub.2                                  
                 0.72  0.099                                              
                            1.523                                         
                                 19    Example of the Invention           
71   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 Invention           
72   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 Invention           
73   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 Invention           
74   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 Invention           
75   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       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 Invention           
77   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 Invention           
78   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 Invention           
79   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 Invention           
80   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 Invention           
81   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 Invention           
82   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 Invention           
83   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 Invention           
84   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 Invention           
85   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 Invention           
86   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 Invention           
87   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 Invention           
88   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 Invention           
89   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 Invention           
90   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 Thickness                                
Specimen                                                                  
     Composition Roughness                                                
                       W.sub.13/50                                        
                            Density                                       
                                 of Sheet                                 
No.  (at %)      Ra (μm)                                               
                       (W/kg)                                             
                            B.sub.8 (T)                                   
                                 (μm)                                  
                                       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 Invention           
92   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 Invention           
93   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 Invention           
94   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 Invention           
95   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 Invention           
96   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 Invention           
97   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 Invention           
98   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 Invention           
99   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 Invention           
100  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           
__________________________________________________________________________