R-T-B-BASED RARE EARTH MAGNET PARTICLES, PROCESS FOR PRODUCING THE R-T-B-BASED RARE EARTH MAGNET PARTICLES, AND BONDED MAGNET

摘要

An object of the present invention is to enhance a coercive force of magnetic particles by promoting formation of a continuous R-rich grain boundary phase in a crystal grain boundary of a magnetic phase of the particles, and to thereby obtain R-T-B-based rare earth magnet particles further having a high residual magnetic flux density. The present invention relates to production of R-T-B-based rare earth magnet particles capable of exhibiting a high coercive force even when a content of Al therein is reduced, and a high residual magnetic flux density, in which formation of an R-rich grain boundary phase therein can be promoted by heat-treating Al-containing R-T-B-based rare earth magnet particles obtained by HDDR treatment in vacuum or in an Ar atmosphere at a temperature of not lower than 670° C. and not higher than 820° C. for a period of not less than 30 min and not more than 300 min.

主权项

1. R-T-B-based rare earth magnet particles comprising R (wherein R represents at least one rare earth element including Y), T (wherein T represents Fe, or Fe and Co), B (wherein B represents boron) and Al (wherein Al represents aluminum), and having an average composition comprising R in an amount of not less than 12.5 atom % and not more than 14.3 atom %, B in an amount of not less than 4.5 atom % and not more than 7.5 atom % and Al in an amount of less than 1.0 atom %, in which the R-T-B-based rare earth magnet particles comprise crystal grains comprising an R2T14B magnetic phase, and a grain boundary phase; and the grain boundary phase comprises R (wherein R represents at least one rare earth element including Y), T (wherein T represents Fe, or Fe and Co), B (wherein B represents boron) and Al (wherein Al represents aluminum), and has a composition comprising R in an amount of not less than 13.5 atom % and not more than 30.0 atom % and Al in an amount of not more than 1.5 atom %.