## Abstract

The five magnetostriction constants $h_{1}$ to $h_{5}$ have been determined for nickel at 4.2, 77 and 300 K from independent measurements on two crystals. At 4.2 K, $h_{3},h_{4}$ and $h_{5}$ are all small compared with $h_{1}$ and $h_{2}$ and there is nothing to suggest that a five-constant equation inadequately represents the magnetostrictive behaviour of nickel at this temperature. Within the temperature range $h_{3}$ is positive, implying that the first anisotropy constant, $K_{1}$, increases under pressure--in agreement with direct measurements. The combinations $h_{1}-\frac{1}{4}h_{3}+\frac{5}{6}h_{4}$ and $h_{2}+\frac{1}{12}+\frac{2}{9}h_{5}$ have been measured at small temperature intervals from 4.2 to 300 K. From these the appropriate combinations of magnetoelastic constants have been determined and their temperature variation compared with the theory of Callen & Callen (1963); agreement is poor. It is concluded that the magnetoelastic constants of nickel do not follow the third power law (nor more general expressions which use the same basis) and that the first anisotropy constant does not obey the tenth power law.