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BELL SYSTEM TECHNICAL JOURNAL 



addition of small amounts of cobalt or nickel, 10 per cent of either 

 being sufficient to reduce the maximum permeability 85 per cent. 

 All of the iron-nickel alloys between 35 per cent and 85 per cent nickel 

 have as high or higher permeability than Armco iron. 



16000 



Fig. 5 — Maximum permeabilities for annealed alloys. 



I have not prepared a diagram for the maximum permeabilities for 

 the air-quenched alloy. However, I can say that the surface obtained 

 resembles the one shown for the initial permeabilities for the rapidly 

 cooled alloys, although, of course, the maximum permeabilities are of 

 different magnitudes. As high as 120,000 has been obtained for the 

 alloy containing 78.5 per cent nickel. 



