MAGNETIC MATERIALS IN RELATION TO STRUCTURE 



35 



that appreciably higher coercive forces are available in the one con- 

 sisting of iron, cobalt and molybdenum. In Fig. 17 are shown the 

 combinations of residual induction and coercive force obtained by 

 Koster in the latter system with variations in molybdenum and cobalt 

 content. Coercive forces of over 200 oersteds, associated with residual 

 inductions of approximately 10,000 gauss, are given. 



Fig. 16 — Structure of the same alloy shown in Fig. 15 after a subse([uent aging 

 treatment of 24 hours at 1000° C. This treatment has resulted in the precipitation 

 of a large amount of the second phase. Mag. 125 X. 



The desirable properties of this class of materials are developed by a 

 double heat treatment which consists of a quench from a high tempera- 

 ture followed by aging at a lower temperature. The alloys are precipi- 

 tation hardening in the same manner as the non-ferrous copper- 

 beryllium alloys or lead-calcium cable sheath alloys. The heat treat- 

 ment is illustrated in Fig. 18, which shows the effect of aging on the 



