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%/[degrees] 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 100 [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 powder 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-Ti-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 stability and corrosion resistance.