Magnetic hysteresis of mechanically alloyed Sm–Co nanocrystalline powders

Mechanically alloyed Sm–Co powders and Sm12 (Co,Cu,Ti) 88 powders are investigated. X-ray diffraction patterns show that after annealing, structures of 2:7, 1:5, and 1:7 phases form. A room-temperature coercivity of 41 kOe was obtained in Sm2Co7 powders. Magnetic hysteresis was investigated by the method of δ m curves. Positive value δ m curves were obtained in Sm2Co7 and SmCo5, while negative values were found in SmCo7.3 and SmCo8 indicating different magnetization reversal mechanisms. Nanocrystalline powders of Sm12 (Co,Cu,Ti) 88 with a mixture of 1:5 and 2:17 phases form after long-time heat treatment. The intrinsic coercivity of the powders increases with an increasing amount of Cu. Short annealing time produces 1:7 phase with higher crystalline anisotropy, which results in larger coercivity