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 investig ated 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% /degree s C and -0.43 % /degrees C, respectively, in the temperature range of 25 to 100 degrees C range. Irreversible loss of Sm-Fe-Ti-B-N bonded magnet at 10 0 degrees 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 po wder is evaluated by measuring increase in oxygen content after exposure at 120 degrees C. It is compared with Sm-Fe-N and Nd-Fe-Co-B powders. Sm-Fe-T i-B-N powder shows slight increase in oxygen content after exposure at 120 degrees C in air for 300 hrs. It is also found to have good thermal stabili ty and corrosion resistance.