| 摘要 |
PURPOSE:To stably produce an anisotropic rare-earth alloy powder for the permanent magnet having a high coercive force and a large magnetic anisotropy by heat-treating the fine powder of a rare-earth element-Fe-B alloy under speci fied conditions and then hydrogenating the fine powder to form a mixed struc ture contg. rare-earth hydrides. CONSTITUTION:An alloy consisting of 10-20 atomic % of R (rare-earth elements including Y contg. <=50 atomic % of at least one kind between Pr and Nd), 67-85 atomic % of T (Fe or a part of which is replaced by <=50% Co), 4-10 atomic % of B or further <10 atomic % of M (>= one kind among Al, Ti and other metals) is roughly crushed to obtain a powder in which >=80wt.% of the grains having 50-5000mum average size consist of a tetragonal Nd2Fe14B type compd. The powder is heated to >=750 deg.C in a heating furnace filled with an Ar gas atmosphere, then gaseous H2 at 10-1000kPa is introduced into the furnace the mixture is heated to 750-950 deg.C to form a four-phase mixed structure of the R hydrides, a T-B compd., a T phase and an R2T14B compd., and the mixture is dehydrogenated at 700-900 deg.C and then cooled. |
