| 简介 |
PROBLEM TO BE SOLVED : To provide a high-performance rare earth magnet to obtain high coercive force or high residual magnetic flux density even when saving rare earth element content of such rare resources as Dy.
SOLUTION : An Nd-Fe-B magnet has been applied with mechanical working to be a predetermined shape and measure, and includes a crystal grain boundary layer rich in Nd element inside. In the crystal grain boundary layer, density of M element (M is one or more than two kinds of rare earth elements selected from Pr, Dy, Tb, and Ho) is enriched by dispersion and penetration of M element from a magnet surface. A dispersion and penetration amount of the M element satisfies the following formulae. Formula 1 : Hcj≥1+0.2×M (0.05≤M≤10), Hcj : coercive force, unit (MA/m), M : M element content accounting in total magnet (mass%). Formula 2 : Br≥1.68-0.17×Hcj, Br : residual magnetic flux density, unit (T). And the Hcj is not less than 1.19 times coercive force of the magnet before forming a film.
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