Magnetostriction Constants of Nickel-Cobalt Alloys

Abstract

The magnetostriction constants, λ 100 and λ 111 , of f.c.c. Ni-Co alloys have been measured in the temperature range between 77 and 450 K using the strain gauge technique. The sign of λ 100 changes from negative to positive with increasing Co content in the temperature range between 77 and 450 K, while the values of λ 111 are negative. The magnitude of both constants decreases monotonically with increasing temperature. The present data were analyzed by Néel's theory and the coefficient of pseudo-dipole interaction was estimated. The temperature dependence or the magnetoelastic coupling constants does not obey the third power law of the reduced magnetization. The contribution of the magnetoelastic coupling effect to the anisotropy constant, K 1 , were evaluated. The contribution is too small to explain the change of sign in K 1 with increasing temperature and/or Co concentration.