Rare earth-iron-boron permanent magnet - has main phase free from tin and an additional tin-contg. phase

摘要

In a permanent magnet having the compsn. 8-30 at% RE (= rare earths including Y), 0.1-2 at% Sn, 2-28 at% B and balance Fe and contg. the tetragonal phase RE2Fe14B as main phase, the novelty is that the RE2Fe14B main phase is free from Sn and that the permanent magnet has a Sn-contg. additional phase contg. RE, Fe and Sn, pref. RE6Fe13Sn. Also claimed is a Sn content is added in the form of one or more Sn-contg. powders before compaction during prodn. of the permanent magnet by compacting alloy powders and then sintering. ADVANTAGE - Magnet has higher coercive field strength and improved temp. dependency of coercive field strength than conventional FEFeB permanent magnets.