Sm 2 (Co,Fe,Cu,Zr) 17 magnets for use at temperature ⩾400 °C

Sintered ${\mathrm{Sm}}_{\mathrm{2}}{\mathrm{(Co,Fe,Cu,Zr)}}_{\mathrm{17}}$ magnets with improved high temperature performance have been obtained by reducing the iron content in the magnet alloys. A record intrinsic coercive force, ${}_I{H}_C,$ of 8.3 kOe at 400 $°\mathrm{C}$ was obtained when the iron content was decreased to 7 wt%. At 400–600 $°\mathrm{C},$ 2:17 magnets with low iron content have demonstrated lower irreversible loss of magnetic flux, higher maximum energy product, and lower temperature coefficient of ${}_I{H}_C.$ A temperature coefficient of ${}_I{H}_C\text{=−0.12\%/°}\mathrm{C}$ (20–400 $°\mathrm{C})$ was obtained for the low Fe magnets, compared to −0.23%/$°\mathrm{C}$ for commercial 2:17. Reducing iron content increases both Curie temperature and anisotropy field. Therefore, it is anticipated that new 2:17 magnet materials capable of operating at 400 $°\mathrm{C}$ or higher temperatures can be developed by reducing or eliminating the iron content and making other adjustments in composition and heat treatment.