440 BELL SYSTEM TECHNICAL JOURNAL 



and were plotted either against the flux density or the magnetizing 

 force, depending on which graph illustrated best the characteristics 

 of the material. At the lower ends these curves were extended to 

 zero field strengths. Their intercepts on the permeability axis are 

 the initial permeabilities. The maximum permeabilities were also 

 obtained from these curves. 



For determining hysteresis loss, two methods were used. In some 

 cases hysteresis loops were plotted from ballistic measurements, and 

 in other cases a direct determination of hysteresis loss was made from 

 the apparent alternating-current resistance of a winding wrapped 

 around the sample. Ordinarily the hysteresis loop was obtained for 

 one condition only in which the flux density was varied between plus 

 and minus 5,000 gauss. For some of the alloys of special interest, a 

 large number of loops were obtained for difl^erent magnetizations, 

 the maximum flux densities varying from 100 or less to 5,000 gauss. 



In illustrating the magnetic properties I will be forced to limit 

 the discussion to a few outstanding values for each alloy, and by 

 comparing these, obtain a general view of the relation of the magnetic 

 properties to composition. The values I have selected are the intrinsic 

 inductions for two magnetizing forces, 50 and 1,500 gauss respectively, 

 the initial and the maximum permeabilities and the hysteresis loss 

 for a maximum flux density of 5,000 gauss. For a number of alloys 

 which represent regions of composition with magnetic properties of 

 special interest, curves for magnetization and permeability will be 

 shown. A number of hysteresis loops for difi^erent maximum flux 

 densities will also be given. 



In illustrating graphically the relations between the magnetic 

 properties and compositions of ternary alloys, it is convenient to 

 plot these quantities in the form of solid diagrams. Such a diagram is 

 shown in Fig. 3 constructed for initial permeabilities of the alloys in 

 the annealed condition. In this figure the composition triangle. Fig. 1, 

 is used as the base. On this triangle, verticals are erected proportional 

 to the numerical values of the initial permeability. The ends of these 

 verticals give a contour of the upper face of the figure. With a 

 sufficient number of alloys this surface represents fairly accurately 

 the values of the initial permeabilities for all compositions. The 

 edges of the surface give the initial permeabilities of the binary alloys 

 and the rest of the surface those of the ternaries. 



The coordinates of the composition triangle, the intersections of 

 which give the compositions of the alloys in 10 per cent variations, 

 are projected to the surface and are represented by the narrow black 

 lines. The heavy black lines on this surface are contours such as 



