Patent ID: 6471786
Filing Date: 2002-10-29
Classification: B22F,B82Y,C22C,H01F,Y10S

Abstract:
A method for preparing nanocomposite magnet powder, the method comprising the steps of:preparing material alloy powder for a nanocomposite magnet, the powder being represented by a general formula Fe100âˆ’xâˆ’yRxBy, Fe100âˆ’xâˆ’yâˆ’zRxByCoz, Fe100âˆ’xâˆ’yâˆ’uRxByMu or Fe100âˆ’xâˆ’yâˆ’zâˆ’uRxByCozMu where R is a rare-earth element; 78-100 atomic percent of R is Pr and/or Nd, 0-22 atomic percent of R is another lanthanoid and/or Y; M is at least one element selected from the group consisting of Al, Si, Ti, V, Cr, Mn, Ni, Cu, Ga, Zr, Nb, Mo, Hf, Ta, W, Pt, Pb, Au and Ag; the molar fractions x, y, z and u meet the inequalities of 2&lE;x&lE;6, 16&lE;y&lE;20, 0.2&lE;z&lE;7 and 0.01&lE;u&lE;7, respectively, the powder including a metastable phase and an amorphous structure existing in a metal structure; and heat-treating said material alloy powder to crystallize Fe3B and Feâ€”Râ€”B compounds from the amorphous structure, wherein an integral value of the difference between a temperature-time curve represented by the temperature of the material alloy powder for the nanocomposite magnet and the heat treatment time in the step of heat-treating the material alloy powder for the nanocomposite magnet and a reference temperature-time curve is in a range from 10Â° C.Â·sec to 10,000Â° C.Â·sec, said reference temperature-time curve being obtained by heat-treating said material alloy powder for said nanocomposite magnet for an equivalent amount of alloy having the same composition as said material alloy for the nanocomposite magnet without said amorphous structure.