HIGH-COERCIVITY IRON-RICH RARE-EARTH PERMANENT-MAGNET MATERIAL BASED ON (FE, CO)3B-ND-M (M=AL, SI, CU, GA, AG, AU)

High-coercivity, high-remanence permanent magnet materials have been o btained via a crystallization treatment of amorphous (Nd,Dy)xFe80.5-x- yCoyB18.5M1 alloys for 3 less-than-or-equal-to x less-than-or-equal-to 5 and 0 less-than-or-equal-to y less-than-or-equal-to 5, where M repr esent the additives Al, Si, Cu, Ga, Ag, and Au. It has been found that addition of Co and M results in a significant reduction of the crysta l grain size and leads to significant improvements both in the intrins ic coercivity and in the energy product. The materials are superior to Nd2Fe14B-based rapidly solidified materials in the remanence B(r), th e temperature coefficient of B(r) and magnetizability. The typical val ues of temperature coefficients of B(r) and H(cJ) are, respectively, - 0.05%/K and -0.35% K. The magnetizing force required to obtain substan tial remanence is approximately 0.8 MA/m. Compaction-molded resin-bond ed magnets produced from these materials have magnetic performance (B( r), H(cJ)) in the range between 0.89 T, 0.29 MA/m and 0.80 T, 0.35 MA/ m.