The effects of MM38.2Co46.4Ni15.4 alloy additions on the mechanical properties of a Nd12.8Fe79.8B7.4-type sintered magnet

The mechanical properties of the Nd–Fe–B-based alloys are closely related to their microstructures. It was found that the Co and Ni additions to the Nd2Fe14B (Φ) matrix phase and reduction in the amounts of rare earth (RE)-rich (n) and B-rich (η) grain boundary phases are very effective in improving the mechanical properties. The addition of a MM38.1(MM: Misch Metal)–Co46.4–Ni15.5 alloy to a ternary Nd12.8Fe79.8B7.4-type alloy by a binary powder blending technique resulted in a considerable increase in bending and compressive strength, and a significant decrease in impact strength. The solid solution hardening of the matrix phase by Co and Ni and the presence of intergranular cracks within the grain boundary phase(s) could be the main factors involved in the mechanical behaviors of these alloys.