Soft Ferromagnetic properties of some amorphous alloys

Abstract

In rapidly quenched amorphous alloys (Fe 1 − x Co x ) 80 P 13C 7 and (Fe 1 − x Co x 75Si 15B 10, the zero magnetostrictive alloys are remarkably soft magnetic materials, while the magnetostrictive alloys have rather large coercive forces [1]. To investigate the effect of magnetostriction on the properties of the BH loop, some fundamental magnetic properties of these alloys were studied. The magnetic domain pattern observed by Bitter's method shows a periodic domain structure consisting of 180° and maze domain walls in all the magnetostrictive alloys, suggesting the existence of a magnetic anisotropy with an easy axis that varies locally. The estimated value of the anisotropy energy varies with x similarly to the concentration dependence of the magnetostriction. The coercive force also varies with x and is nearly proportional to the ratio of the magnetostriction to magnetization. It is, therefore, considered that the anisotropy is caused by the anisotropic internal stress field, and that the stress fluctuation which inevitably exists is responsible for the large coercive force.