448 



BELL SYSTEM TECHNICAL JOURNAL 



in the direction of rolling ^^ (see Table IV). Such materials have 

 been used to some extent abroad for loading coil cores. Aside from 

 the difficulty of attaining as low hysteresis loss, high permeability, and 

 high stability as obtainable with permalloy powder cores, such ma- 

 terials appear to be at an economic disadvantage because of the high 

 cost of rolling sheet thin enough for eddy current loss reduction. 



Stresses well within the elastic limit increase or decrease the permea- 

 bility of materials, depending on the composition. -° Furthermore, 

 tension and compression generally have opposite effects. The changes 

 in permeability due to such weak stresses are not permanent, but 

 practically disappear when the stress is removed. 



Cost of Magnetic Materials 



Many materials having very desirable technical qualifications can- 

 not be used extensively because of their high costs. Thus, nickel at 

 2>Sil\h., cobalt at $1.35/lb., tungsten at $1.80/lb., and vanadium at 



COMPOSITION MATERIAL 



IN PER CENT 

 IRON NICKEL OTHER 



95 3C 2SL 

 99.94 



99.3 0.5 SI 



96 451 



54.4 45 0.6 Mn 

 20.9 78.5 0.6 Mn 

 16.4 79 4 MO 0.6 Mn 

 16.4 79 4Cr 0.6 Mn 

 17 81 2 MO 



50 50 Co 



49 49C02V 



29.4 45 25CO 0.6 Mn 



21.9 45 25C0 7 5M00.6Mn 75-45-25 PERM INVAR 



85 9.5 SI 5.5 Al SENDUST 



COST 



IN CENTS PER POUND 

 20 40 60 



58 

 71 

 55 



CAST IRON 



MAGNETIC IRON 



Si IRON, FIELD 



Si IRON, TRANSFORMER 



45 PERMALLOY 

 78.5 PERMALLOY 

 4-79 MO PERMALLOY 

 4-79 Cr PERMALLOY 

 2-81 MO PERMALLOY 



PERMENDUR 

 V-PERMENDUR 

 45-25 PERMINVAR 



98 I Cr 0.6C 0.4 Mn 1 % Cr STEEL 



95.6 3Cri.0C0.4Mn 3°/oCrSTEEL 



1 c 3 5Cr 7W \ 



52 36Coa5Mn/ HONDA KS STEEL 



44.6 18 27Co 6.7TL 3.7A1 HONDA, NEW 



29 



13 A1 



I7M0 12CO 

 I6CO 290 



MISHIMA STEEL 



REMALLOY 



OXIDE 





Fig. 3 — Raw materials cost of various magnetic alloys. 



"O. V. Auwers, Wiss. Ver. a.d. Siemens-Werk. 15, 112 (1936). 

 200. E. Buckley & L. W. McKeehan, Phys. Rev. 26, 261 (1925). 



