The sintered alloy strip for permanent magnet and a permanent magnet

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PROBLEM TO BE SOLVED : To produce an alloy thin strip for a permanent magnet in which a four phase coexistent region is positively activated and magnetic properties are improved. SOLUTION : This alloy thin strip for a permanent magnet is obtd. by rapidly cooling an alloy melt mainly consisting of R, T and B (R denotes rare earth elements selected from Pr, Nd, Tb and Dy, and T denotes metals selected from Fe, Co, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Sn, Sb, Ta, W and Pb). In this case, the volume ratio of a four phase coexistent region, in which an α-Fe phase of 0.1 to 20 μm particle size, an R rich phase of 0.1 to 20 μm, an RxT4B4 phase of 0.1 to 10 μm and an R2T14B phase of 0.1 to 20 μm are finely dispersed, is 1 to 10% in the total volume, and the balance other than the four phase coexistent region is composed of an R rich phase, an RxT4B4 phase and an R2T14B phase or an R rich phase and an R2T14B phase. The volume ratio of the four phase coexistent region is preferably controlled to 2 to 5% in the total volume.