Microstructure and Magnetic Properties of Sm (CobalFe0.28Cu0.06Zr0.02)7.84 Magnet Prepared by Hydrogen Decrepitation and Mechanical Crushing

Two methods of pre-crushing power, hydrogen decrepitation (HD) and mechanical crushing (MC), were applied to prepare Sm (CobalFe0.28Cu0.06Zr0.02)7.84 magnets. Their microstructures and magnetic properties were investigated. Compared with a conventional MC method, the Sm2O3 content was decreased and the coercivity was enhanced from 8.67 to 24.03 kOe with an HD method. The larger grain size and less grain boundaries defects were obtained in HD magnets. In addition, the HD technology improved effective Sm content of magnets by decreasing oxidation of Sm. The effective Sm content played a significant role on microstructure and magnetic properties changes of the two kinds of magnets. In combinations with the changes of alloy composition and microstructures, the effect of HD technology on effective Sm content was discussed.