16 



BELL SYSTEM TECHNICAL JOURNAL 



Elmen ^^ has investigated alloys containing more than 30 per cent 

 of nickel which are characterized by great magnetic softness and have 

 been called "permalloys," ^^ the name suggesting high permeability. 

 These alloys in the region of 40-55 per cent nickel find industrial ap- 

 plication as soft magnetic materials. They are used in telephone and 

 radio transformers and telephone relays. An alloy typical of this 

 region is the one containing 45 per cent of nickel. A curv^e ^' showing 



1600 



-'00 



20 I 40 f 60 faO 100 



NICKEL - PER CENT 

 Fig. 5 — The constitutional diagram of iron and nickel. 



the permeability of this alloy is plotted in Fig. 6. From the data given 

 on this curve, the material exhibits an initial permeability of 2000 and 

 a maximum permeability of 16,000. 



Another alloy in this region is the one containing 50 per cent of 

 nickel which has been investigated by Yensen. He has applied the 

 name "Hypernik" ^" to it. Yensen, by giving this material a special 

 heat treatment, obtained an initial permeability of 4000 and maximum 

 permeability of 70,000. 



