| 简介 |
PURPOSE : A rare earth permanent magnet is provided to give an R-Fe-B based sintered magnet using the small amount of Tb or Dy and to have high performance of a magnetic characteristic.
CONSTITUTION : A rare earth permanent magnet is a sintered magnet body having a composition of R1aR2aTcAdFeOfMg. R1 is one or two kinds selected from rare earth elements including Sc and Y and excluding Tb and Dy, R2 is one or two kinds selected from the Tb and Dy, T is one or two kinds selected from Fe and Co, A is one or two kinds selected from B and C, M is one or two kinds selected from Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W, and a - g are atom percents of alloy in a range of 10<=a+b<=15, 3<=d<=15, 0.01<=e<=4, 0.04<=f<=4, 0.01<=g<=11 and c is a balance. The F and R2 are distributed so that the average concentrations get denser as goes from the center of the magnet body to the surface of the magnet body. In a grain boundary unit surrounding a columnar grain composed of a (R1, R2)2T14A tetragon, the concentration of R2/(R1+R2) included in a grain boundary is averagely denser than that of R2/(R1+R2) of the columnar grain, the acid fluoride of (R1, R2) exists in the grain boundary unit to a depth of at least 20um from the surface of the magnet body of the grain boundary unit.
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