FACTORS AFFECTING MAGNETIC QUALITY 



279 



high resistivity of the ferromagnetic elements compared to their neighbors 

 in the periodic table and (2) the relative amounts by which the resistivity 

 of iron (or cobalt or nickel) is raised by a given atomic percentage of vari- 

 ous other elements. From a practical standpoint, a high resistivity is usually 



AGING TEMPERATURE IN DEGREES CENTIGRADE 



O 



IL 



Uj 0.8 



200 300 



TIME IN HOURS 



Fig. 28 — Effect of nitrogen impurity on the coercive force of iron annealed successively 

 at 100 and 150°C. 



U 22 



2 16 



<^ 



> 12 



a 10 



06 0.8 1.0 1.2 1.4 



PER CENT OF ALLOYING ELEMENT IN IRON 



to 



Fig. 29 — Dependence of resistivity on the addition of small amounts of various elements 

 iron. 



desirable in order to decrease the eddy-current losses in the material, and 

 so decrease the power wasted and the lag in time between the cause and 

 effect, for example, the time lag of operation of a relay. 



Knowledge of the atomic diameter is important in considering the effects 



