HIGH-PERFORMANCE SM2FE15GA2C2 PERMANENT-MAGNETS MADE BY MECHANICAL ALLOYING AND HOT-PRESSING

The nonequilibrium process of mechanical alloying was used to prepare nanocrystalline Sm2Fe15Ga2C2 powder. The crystallization of the Th2Zn1 7-type structure in mechanically alloyed Sm-Fe(Ga)-C material begins a t about 690 degrees C. The single phase structure can be obtained afte r homogenization for one hour at temperatures between 800 degrees C an d 900 degrees C. The coercivity mu(OJ)H(c) increases to a maximum valu e of about 1.5 T after annealing at a temperature of 850 degrees C. Th e nearly square shape of the demagnetization curve suggests a very hom ogeneous microstructure of the highly coercive powder. By hot pressing , a fully dense Sm2Fe15Ga2C2 magnet was successfully obtained with a d ensity of 7.6 g cm(-3) and a coercivity of 1.5 T. No texture could be observed after a 75% hot deformation at 800 degrees C.