MAGNETIC PROPERTIES OF PERMINVAR 



33 



more rapid cooling rate had been used these characteristics no doubt 

 would have disappeared completely. The hysteresis loops all have 

 considerable areas. The one for 568 gauss, the lowest flux density 

 measured, represents an energy loss of 18.7 ergs per centimeter cube. 

 For the same flux density, the hysteresis loops for the annealed and 

 the baked rings have no measurable areas, the ascending and de- 

 scending branches of the loops falling on the straight lines shown in 



100 -, 



100 



Fe 



Fig. 9 — Composition diagram Ni — Fe — Co Series. Area enclosed by the curve 

 shows compositions with marked Perminvar characteristics 



the figure. This absence of measurable area extends up to a flux 

 density of nearly 1,000 gauss for the baked ring. The increase of 

 energy loss as the flux density increases above this value, however, 

 is considerably more rapid than for the quenched ring. At 1,500 

 gauss, the hysteresis loss is a little greater than for the quenched ring 

 and when the flux density is increased to 5,000 gauss, the loss is more 

 than double. 



It was shown above that the degree to which perminvar charac- 



3 



