Thermal stability and oxidation resistance of HDDR processed Sm-Fe-Ti-B-N bonded magnets

Thermal stability of HDDR processed Sm-Fe-Ti-B-N bonded magnets is investigated in comparison with HDDR processed Sm-Fe-N bonded magnets. Temperature coefficients of Br and iHc of Sm-Fe-Ti-B-N bonded magnet are -0.06%//spl deg/C and -0.43%//spl deg/C, respectively, in the temperature range of 25 to 100/spl deg/C range. Irreversible loss of Sm-Fe-Ti-B-N bonded magnet at 100/spl deg/C is -2.1% and -2.5% respectively after exposure for 2 hrs and 300 hrs. This irreversible loss of Sm-Fe-Ti-B-N is lower than that of Sm-Fe-N which has coercivity 16 kOe. The corrosion resistance of Sm-Fe-Ti-B-N powder is evaluated by measuring increase in oxygen content after exposure at 120/spl deg/C. It is compared with Sm-Fe-N and Nd-Fe-Co-B powders. Sm-Fe-Ti-B-N powder shows slight increase in oxygen content after exposure at 120/spl deg/C in air for 300 hrs. It is also found to have good thermal stability and corrosion resistance.