Rare earth–cobalt permanent magnets with improved mechanical properties

Abstract

A rare earth–cobalt permanent magnet with improved mechanical strength has been developed. Sm1−uCeu(Co1−x−yCuxTmy)z with Tm=Fe or a combination of Fe with other transition metals were prepared by powder-metallurgical means. Mechanical strength was evaluated by flexural strength testing for sintered permanent magnet rods. The compositional dependence on flexural strength σf as well as the influence of the different parameters, as for instance particle size and sintering temperature, were investigated. For z ≳ 5, σf increases with increasing z and other substitution parameters u, x and y. For instance, fine grained magnet of Sm0.8Ce0.2(Co0.785Cu0.15Fe0.05 Cr0.015)7.6 shows σf of 290 MPa, iHc of 360 kA/m and Br of 0.85 T.