Dependence of the Magnetic Anisotropy on the Alloy Composition in Cold-Rolled Vicalloy Magnet

Abstract

Specimens of the permanent magnet alloy “Vicalloy” composed of 2∼6% Cr, 6∼10% V, 52% Co and balance Fe were reduced to 93% by cold rolling and subsequent tempering at temperatures between 20° and 800°C. The measured magnetic properties were saturation induction, residual induction, coercive force and magnetic torque. Severe cold rolling produces the uniaxial roll magnetic anisotropy, in which the easy magnetic direction is perpendicular to the rolling direction. In the cold-rolled state, the lower the (Cr+V) content of Vicalloy, the larger is the roll magnetic anisotropy. After tempering the cold-rolled Vicalloy at 350°∼400°C, the residual induction and the coercive force in the rolling direction take the same values as in the cross direction, and the roll-magnetic anisotropy disappears. By tempering at 500°∼600°C, the easy magnetization direction becomes parallel to the rolling direction and the maximum value of coercive force is obtained. As the (Cr+V) content increases, the coercive force increases, but the saturation magnetization decreases. The permanent magnet characteristics of Vicalloy may be explained by an uniaxial magnetic anisotropy which may be caused by either the shape anisotropy or the strain anisotropy of the specimen.