Rare earth permanent magnets and their preparation

摘要

A sintered magnet body (R a T 1 b M c B d ) coated with a powder mixture of an intermetallic compound (R 1 i M 1 j , R 1 x T 2 y M 1 z , R 1 i M 1 j H k ), alloy (M 1 d M 2 e ) or metal (M 1 ) powder and a rare earth (R 2 ) oxide is diffusion treated. The R 2 oxide is partially reduced during the diffusion treatment, so a significant amount of R 2 can be introduced near interfaces of primary phase grains within the magnet through the passages in the form of grain boundaries. The coercive force is increased while minimizing a decline of remanence.