Partial substitution of SM with neodymium, praseodymium, and mischmetal in RE2TM17permanent magnets

High coercive force Sm2(Co,Fe,Cu,Zr)17type magnets with Sm partly replaced by neodymium, praseodymium and mischmetal were investigated. Magnetic properties including open circuit temperature effects on remanence were measured for these magnets. The results show that coercive force began to decrease when Sm was substituted with any of the rare earths investigated. Usable coercive force can still be maintained at more than 50% substitution of Sm by mischmetal and up to 20% substitution by neodymium. With neodymium and praseodymium substitutions, the expected increase of residual induction Br did not occur, presumably due to lessened orientation. Open circuit remanence measurements show that these magnets have temperature effects only slightly higher than the Sm only magnet and are better than the new neodymium-iron-boron magnet.