MAGNETIC ALLOYS OF IRON, NICKEL, AND COBALT 461 



particular compositions. I cannot at this time go into a detailed 

 discussion of the results with these, but I shall mention briefly some of 

 them. We found that the addition of some of the non-magnetic 

 metals to both the permalloys and the perminvars made those alloys 

 less sensitive to heat treatment. The resistivity was also generally 

 increased. For some compositions the addition in small percentages 



40000 



30000 



M 



20000 



10000 



.01 



H 



.02 



.03 



Fig. 20 — Permeability curves for permalloys. 



of a non-magnetic metal, particularly chromium and molybdenum, 

 increases the permeability at low magnetizing forces. This is illus- 

 trated in Fig. 20 where I have plotted the permeability curves for 

 Armco iron, 78.5 permalloy, and a 3.5-78.5 Mo-permalloy. You will 

 note that the initial permeability of the molybdenum-permalloy 

 alloy is 21,000 as compared with 9,000 for the permalloy without 



