CHANGE OF ELASTIC CONSTANTS OF FERROMAGXETrCS. 05 



From the above table, it will he seen that the Poisson ratio 

 is generally diminished by magnetization. In nickel, it is very 

 large amounting to even 50 per cent; l)ut in tungsten steel, it 

 is almost zero, indicating a tendency to increase. The change of 

 the Poisson ratio also considerably varies ^Yitll tension, and the 

 above table shows only an example of the change. 



§ 4. CONCLUDING REIVIARKS. 



The results obtained in the present investigation may be 

 summarised as follows : — 



(i) In Swedish iron and tungsten steel (Figs. 71 and 72), 

 the change of elastic constants is generally positive, l)ut its 

 amount is extremely small, less than 0.5 fo. The change by the 

 indirect method is several times greater than that by the direct 

 method. It is interesting to notice that the change of elasticity 

 and that of rigidity almost coincide with each other, not only in 

 their general aspects, but also in their quantitative relations. 



(ii) In nickel (Fig. 73), the change of elastic constants is 

 remarkably large, amounting to about lofo in the change of 

 elasticity and 7^o in the case of rigidity. The elastic constants 

 first decrease and then increase, as the field becomes greater. 

 The elastic constants by the indirect method are numerically 

 greater than those by the direct method. 



(iii) In 28. 74% Ni. (Fig. 74), magnetization increases the 

 elastic constants by a small amount. The changes given by the 

 two different methods nearly coincide with each other for a mode- 

 rate tension. In Ö0.72 % Ni. and 70.32 ?« Ni. (Figs. 75 and 76), 

 the increase of the elastic constants is remarkably large, approach- 

 ins; in amount the change of rigidity in nickel. Except with a 



