RARE EARTH PERMANENT MAGNET

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PURPOSE : A rare earth permanent magnet is provided to increase coercivity by distributing Dy or Tb and F to make the average concentration of the Dy or Tb, and F denser from the center of a magnet to the surface of the magnet. 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 to 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 thereof get denser as goes from the center of the magnet body to the surface of the magnet body. The rare earth permanent magnet has a three dimensional network shape that a grain boundary of which the concentration of R2/(R1+R2) is averagely denser than the concentration of R2/(R1+R2) of a columnar grain composed of a (R1, R2)2T14A tetragon is continuously formed from the surface of the magnet body to a depth of at least 10um. © KIPO 2006