Sm-2(Co,Fe,Cu,Zr)(17) magnets for use at temperature >= 400 degrees C

Sintered Sm-2(Co,Fe,Cu,Zr)(17) magnets with improved high temperature perfo rmance have been obtained by reducing the iron content in the magnet alloys . A record intrinsic coercive force, H-l(c), of 8.3 kOe at 400 degrees C wa s obtained when the iron content was decreased to 7 wt%. At 400-600 degrees C, 2:17 magnets with low iron content have demonstrated lower irreversible loss of magnetic flux, higher maximum energy product, and lower temperatur e coefficient of H-l(c). A temperature coefficient of H-l(c)=-0.12%/degrees C (20-400 degrees C) was obtained for the low Fe magnets, compared to -0.2 3%/degrees C for commercial 2:17. Reducing iron content increases both Curi e temperature and anisotropy field. Therefore, it is anticipated that new 2 : 17 magnet materials capable of operating at 400 degrees C or higher tempe ratures can be developed by reducing or eliminating the iron content and ma king other adjustments in composition and heat treatment. (C) 1998 American Institute of Physics. [S0021-8979(98)19111-9].