R-T-B-TYPE SINTERED MAGNET AND METHOD FOR PRODUCTION THEREOF

摘要

Disclosed is an R-T-B-type sintered magnet which has the following chemical composition: R: 27.3 to 29.5 mass% (inclusive), B: 0.92 to 1 mass% (inclusive), Cu: 0.05 to 0.3 mass% (inclusive) and M: 0.02 to 0.5 mass% (inclusive), with the remainder being T, and has an oxygen content of 0.02 to 0.2 mass%, wherein the main phase of the sintered magnet comprises a R2T14B-type compound, the main phase has a crystal particle diameter of 8 µm or less in terms of circle-equivalent diameter, and the surface area occupied by crystal particles each having a size of 4 µm or less makes up 80% or more of the whole surface area of the main phase.