Magnetic properties of a new type of rare-earth cobalt magnets Sm<inf>2</inf>(Co, Cu, Fe, M)<inf>17</inf>

The effects of various additive elements on the magnetic properties of Sm-Co-Cu-Fe quaternary alloys were studied. It was found that zirconium was the best additive element for improvement of their magnetic properties. The best properties were so far obtained for an alloy of Co, 25.5wt% Sm, 8wt% Cu, 15wt% Fe, 1.5wt% Zr. The energy product of this alloy attains 30MGOe by a step tempering following the solution treatment. In addition to excellent magnetic properties, Sm 2 (Co, Cu, Fe, Zr) 17 type permanent magnets exhibited the desirable temperature coefficient of residual magnetization of 0.03%/°C and a temperature coefficient of intrinsic coercive force of 0.16%/°C.