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

$\mathrm{Sm}({\mathrm{Co}}_{\mathrm{bal}}{\mathrm{Fe}}_{\mathrm{0.1}}{\mathrm{Cu}}_x{\mathrm{Zr}}_{\text{0.033}}{)}_z$ magnets with higher Cu content were found to have higher intrinsic coercivity $H_{\mathrm{ci}}$ at both room temperature and higher temperatures up to 500 °C. For the magnets with a ratio $\text{z=8.5,}$ 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 $\text{z=7.0,}$ 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 °C was obtained on a ${\mathrm{Sm(Co}}_{\mathrm{bal}}{\mathrm{Fe}}_{\mathrm{0.1}}{\mathrm{Cu}}_{\mathrm{0.128}}{\mathrm{Zr}}_{\text{0.033}}{)}_z$ magnet.