FUNCTIONAL-GRADIENT RARE-EARTH PERMANENT MAGNET

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FIELD : metallurgy. SUBSTANCE : functional-gradient magnet has a composition R1 aR2 bTcAdFeOfMg, where R1 is one of rare earth elements, including Sc and Y and excluding Tb and Dy, R2 - Tb and/or Dy, T is iron and/or cobalt, A is boron and/or carbon, F is fluorine, O is oxygen, and M is at least one of 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. Indices a-g indicate atomic percent contents and have the following values : 10 ≤ a+b ≤ 15, 3 ≤ d ≤ 15, 0.01 ≤ e ≤ 4, 0.04 ≤ f ≤ 4, 0.01 ≤ g ≤ 11, c - the rest. Concentration R2/(R1+R2) contained on borders of grains surrounding grains of a primary phase (R1+R2)2T14A of tetragonal system inside sintered body of magnet is higher, than concentration R2/(R1+R2) contained in grains of the primary phase. R2 is distributed so, that its concentration in average increases from the centre to surface of magnet body. Oxy-fluoride (R1, R2) is present on borders of grains in region spreading from surface of magnet body to depth of 20 mcm; also magnet body has surface layer of higher coercive force, than in internal part. EFFECT : permanent magnet possesses improved thermo-resistance. 5 cl, 4 dwg, 2 tbl, 3 ex