Rare earth sintered magnet and process for producing the same

Abstract

In a process of producing an R—Fe—B based rare-earth sintered magnet, first, an R—Fe—B based sintered magnet, including, as a main phase, R2Fe14B type compound crystal grains with a light rare-earth element RL (which is Nd and/or Pr) as a main rare-earth element R, is provided. Next, the surface of the sintered magnet body is coated with an RHM alloy layer including RH (which is at least one rare-earth element selected from Dy, Ho and Tb) and a metal M (which is at least one metallic element selected from Al, Cu, Co, Fe and Ag). Thereafter, a heat treatment is conducted at about 500° C. to about 1,000° C. within a vacuum or an Ar atmosphere, thereby diffusing the metallic element M and the heavy rare-earth element RH inward from the surface of the rare-earth sintered magnet body.

Dependencies are inferred from the claim text.