RARE-EARTH PERMANAENT MAGNET Russian patent published in 2009 - IPC H01F1/53 

FIELD: metallurgy.

SUBSTANCE: invention relates to powder metallurgy, particularly to receiving of sintered rare-earth permanent magnets on the basis of R-Fe-B. Sintered rare-earth permanent magnet of compound R¹ _aR² _bT_cA_aF_eO_fM_g, where R¹ - at least one element, selected from rare-earth elements, including Sc and Y and excluding Tb and Dy, R² - Tb and/or Dy, T - iron and/or cobalt, A - boron and/or carbon, F - fluorine, O - oxygen, M - at least one element, 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. Indexes a-g specified atomic percentage of corresponding elements in ally and allows values: 10≤a+b≤15; 3≤d≤15; 0.01 ≤e≤4; 0.04≤f≤4; 0.01≤g≤11; c - the rest. In magnet body F and R² are distributed so, that its concentration at an everage increases from center to the surface. Grain boundaries envelopes grains of primary phase (R¹,R²)₂T₁₄A of tetragonal system. Concentration R²/(R¹+R²) at grain boundaries is higher than concentration R²/(R¹+R²) in grains. Oxy-fluoride (R¹, R²) presence at grain boundaries in area of boundaries, stretching from the surface of magnet for depth at least 20 mcm.

EFFECT: sintered magnet allows high coercive force and low remanent magnetization.

5 cl, 2 tbl, 3 dwg, 8 ex