Coercive Sm2Co17 powder for the bonded magnet application

Microstructure of ingots with nominal composition of Sm(Co_0.68Cu_0.065Fe_xZr_y) _z, where x=0.25, 0.27 and 0.30, y=0.01, 0.02 and 0.03 and z varies from 7.9 to 8.3, were examined at various homogenizing temperatures and magnetic hardening treatments. It was found that the resulting H_ci is strongly dependent upon the alloy composition and the homogenizing temperature. In general, the H_ci increases as the homogenizing temperature is raised, peaks at a critical temperature, then decreases with increasing homogenizing temperature. This critical temperature may coincide with the solidus curve of the liquid +2:17→TbCu₇ type disordered structure transformation. In general, the single phased microstructure achieved after the homogenizing treatment is necessary to obtain the highest H_ci, after magnetic hardening. For a fixed thermal treatment, the H_ci was found to increase with the Zr_y content