THE INFLUENCE OF ZIRCONIUM ON SM(COFECUZR)7.2 ALLOYS FOR PERMANENT-MAGNETS .1. IDENTIFICATION OF THE PHASES BY TRANSMISSION ELECTRON-MICROSCOPY

An Sm(Co//0//. //6//9Fe//0//. //2//2Cu//0//. //0//6Zr//0//. //0//3)//7//. //2 alloy cast from the melt was exposed to various heat treatments at 1050-850 degree C. The aged alloys were studied by transmission electron microscopy and energy dispersive X-ray-scanning transmission electron microscope microanalysis. The specimens treated at 1050 degree C contain a mixture of Sm//2Co//1//7 and Sm//2Co//7 type phases. Prolonged aging at 850 degree C provokes the additional precipitation of Sm//4Co//1//9 type phase. A treatment similar to that designed for magnet preparation induces the characteristic cellular morphology described in the literature.