The Variation of Young's Modulus with Magnetization and Temperature in Nickel

The relation between Young's modulus, magnetization, and temperature in annealed polycrystalline nickel, 99.7 percent pure, is determined for values of $J$ between zero and saturation, and for values of $T$ between 23.5°C and 400°C. The percent increase in Young's modulus is proportional to $J^2$ between zero and about 0.4 saturation, at all temperatures below 311°C. The total increase in the modulus from the demagnetized to the saturated state is 6.7 percent at 23°, reaches a maximum of 18.7 percent at 185°, and decreases to zero at the Curie point. The results indicate that the theory of this phenomenon offered by Akulov is probably essentially correct but requires modification. The method employed for the measurement of Young's modulus yields at the same time a measure of the coefficient of internal friction of the material. The internal friction decreases with increasing magnetization at all temperatures below the Curie point. In the demagnetized material it reaches a maximum value at the same temperature as does the change in elastic modulus. Its value at magnetic saturation is the same order of magnitude as that of a nonferromagnetic substance.