Magnetic hysteresis of mechanically alloyed Sm-Co nanocrystalline powders

Mechanically alloyed Sm-Co powders and Sm-12(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 deltam curves. Positive value deltam 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 Sm-12(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. (C) 2003 American Institute of Physics.