IRON PHOSPHATE BASED FILM-COATED R-T-B BASED MAGNET AND ITS FORMATION TREATMENT METHOD

PROBLEM TO BE SOLVED : To provide an R-T-B based magnet, which has excellent corrosion resistance and oxidation resistance without containing chromium and coated with a formation film, in which the thermal demagnetization of a magnet raw material is reduced remarkably, and a manufacturing method having the superior economical efficiency of such a formation film-coated R-T-B based magnet. SOLUTION : The coated R-T-B based magnet has an iron phosphate film on the R-T-B based magnet using an R2T14B intermetallic compound (R represents at least one kind of rare earth elements including Y, and T represents Fe or Fe and Co) as a main phase, and there is at least one kind of R (rare earth element) constituting the R-T-B magnet in the iron phosphate film.