Magnetic Phase Analysis of RECo5 Permanent Magnetic Materials

Heat treatment of SmCo5‐material at elevated temperature increases the coercive force. High temperature magnetization and susceptibility measurements up to 1500 K have shown that there is a correlation between the coercive force and the presence of second phases, e. g. RE2Co17 and that annealing at high temperatures reduces the RE2Co17 content. The existence of the RE2Co17 phase is due to several reasons: e. g. RECo5 forms peritectically, loss of RE through oxidation, chemical reactions with impurities and evaporation. RE has to be added in order to compensate for losses, otherwise a heat treatment can not improve the coercive force.