EFFECT OF MECHANICAL GRINDING AND MECHANICAL ALLOYING ON SM2FE17

Mechanical grinding (MG) in Ar and mechanical alloying (MA) in NH3 have been used to prepare Sm2Fe17Nx permanent magnets, where three different kinds of alloy powders, i.e. Sm2Fe17, Sm2Fe17C and Sm2Fe17C2, were used as the starting materials. The heat-treated (1023 K-1.8 ks in Ar) Sm2Fe17 specimen after the MG exhibited the alpha-Fe peak in addition to the Sm2Fe17 peak. The similarly heat-treated Sm3Fe17 specimen, however, consisted of the single Sm2Fe17 phase, and it was confirmed that the nitrided (723 K-21.6 ks in N2) specimen after the MG and heat treatment had a coercivity higher than 1.2 MA m-1. Nitriding has been carried out thoroughly for all the three specimens treated by the MA process in NH3.