Exceptional elevated temperature behavior of nanocrystalline stoichiometric Y2Fe14B alloys with La or Ce substitutions

摘要

Considering that both La2Fe14B and Ce2Fe14B compounds exhibit similar weak temperature-dependent anisotropic fields (H-A) as Y2Fe14B, this work aims to clarify the elevated temperature behavior of melt-spun nanocrystalline La- or Ce-partially substituted stoichiometric Y2Fe14B alloys containing no critical rare earth elements. The results show that La-substituted (Y1-xLax)(2)Fe14B alloys (x = 0-0.5) show exceptional elevated temperature behavior, manifested by the increased coercivity with increasing temperature. For the Ce-substituted (Y1-xCex)(2)Fe14B alloys, only x = 0.1 and 0.2 alloys show the similar trend. Both the temperature coefficient of remanence alpha and coercivity beta can be improved by La-substituted, indicating partial substitution La can effectively enhance the thermal stability of Y2Fe14B alloy. However, excess La or Ce substitution would reduce alpha and beta value, resulting in the deterioration of thermal stability. Highest beta values of 0.05 and - 0.08 have been obtained in (Y0.9La0.1)(2)Fe14B alloy at 300-400 K and (Y0.8La0.2)(2)Fe14B alloy at 300-500 K, respectively. In addition, Ce substitution can effectively enhance the coercivity of Y2Fe14B alloy at room temperature and La substitution does not show a beneficial effect on the room-temperature magnetic properties. This work is beneficial for developing high-performance/cost ratio permanent magnets based on abundant rare earth elements with superior thermal stability.