New rare-earth permanent magnets with an intrinsic coercivity of 10 kOe at 500 °C

Sm(CobalFe0.1CuxZr0.033)(z) magnets with higher Cu content were found to have higher intrinsic coercivity H-ci at both room temperature and higher temperatures up to 500 degrees C. For the magnets with a ratio z=8.5, the intrinsic coercivity reaches a maximum of about 40 kOe at room temperature when the Cu content x reaches 0.088. But for the magnets with a ratio z=7.0, the intrinsic coercivity continues to increase with increasing Cu content x up to 0.128. Microstructure analysis showed that the cell size decreases while the density of lamella phase increases with increasing Cu content. A record high intrinsic coercivity of 10.8 kOe at 500 degrees C was obtained on a Sm(CobalFe0.1Cu0.128Zr0.033)(z) magnet. (C) 1999 American Institute of Physics. [S0021-8979(99)44108-8].