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BELL SYSTEM TECHNICAL JOURNAL 



the initial permeability varies from approximately 100 to more than 

 2,000. With small additions of nickel to iron, the permeability drops 

 gradually until the added amount is approximately 28 per cent of the 

 composition. From that point there is a rapid rise in the permeability 



Fig. 4 — Initial permeabilities for air-quenched alloys. 



with the increase in the nickel content reaching a maximum of over 

 2,000 for the alloy containing approximately 45 per cent nickel. It 

 then decreases as more nickel is added, reaching a second minimum of 

 about 1,200 for 70 per cent nickel and increases again reaching a 

 second maximum of approximately 1,900 at ^3 per cent nickel. 



Another region of special interest is found in the ternary series in 



