Microstructure and properties of step aged rare earth alloy magnets

Alloys with compositions Co-25.5 wt % Sm-8 wt % Cu-15 wt % Fe-3 wt % Zr and Co-Sm-Cu-Fe-1.5 wt % Zr have been step aged to produce magnets with coercive force (iHc) in the range of 10–25kOe, much higher than those reported so far in the literature for the Zr alloys. The high coercive force magnets are typically aged at 800–850 °C for 10–30 hours following the solution treatment at 1150 °C. Subsequently, these are step aged to produce materials …