Structure and magnetic properties of alnico 8 ribbons

Abstract

Alnico 8 ribbons were prepared by melt-spinning and annealing, and the effects of melt-spinning speeds on the structure and magnetic properties were investigated. The results show that all the as-spun ribbons are composed of the α-Fe(Co)-type α1 and the AlNi-type α2. With speed reducing from 40 m/s to 15 m/s, the <100> preferred orientation enhanced, the grain size and the α2 content increased. The as-spun ribbons show the weak hard magnetic properties. Annealing improves the spinodal structure consisting of the strip-like α1 and α2. The annealed ribbons melt-spun at 15 m/s achieve the optimal magnetic properties with the coercivity of 1558.3 Oe and the maximum magnetic polarisation density of 11.3 kGs, which are codetermined by the shape anisotropy of the strip-like α1 phase and the pinning mechanism of the α2 phase to the α1 domains.