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BELL SYSTEM TECHNICAL JOURNAL 



iron-nickel-aluminum alloy after quenching, and after quenching 

 followed by aging at 1000° C. for 24 hours. There is no visual evidence 

 of the second phase in the quenched specimen although some precipita- 

 tion of submicroscopic particles undoubtedly has occurred. In the 

 aged specimen, in Fig. 16, the second phase appears unmistakably. 



Fig. 15 — Typical structure of an iron-nickel-aluminum alloy, containing 25 per 

 cent nickel and 10 per cent aluminum, after cjuenching from 1200° C. in oil. In this 

 condition the alloy has its optnnum permanent magnet quality. Mag. 125 X. 



If on- Cobalt- Molybdenum and Iron-Cobalt-Tungsten Alloys 



The age hardening characteristics of alloys in these systems were 

 established some years ago by Sykes, who developed the alloys for 

 tools. Later, Seljesater and Rogers ^^ reported that these alloys possess 

 pciTnanent magnet characteristics. A detailed report on the magnet 

 properties has been made by Koster.'" Of the two systems, it appears 



