Novel design of self-compensated thermally stable Ce magnets without critical elements
Feng Xia, Qisong Sun, Minggang Zhu, Yu Wang, Yikun Fang, Wei Li
Abstract
A novel design concept was proposed for optimizing the grain boundaries from the theoretical aspect, which could play the self-compensation effect on the thermal stability of the coercivity. The Pr-Nd-Al Ce magnet without critical elements was investigated that experimentally verified the self-compensation effect of grain boundaries structure on the thermal stability of the coercivity. As a result, the Pr-Nd-Al Ce magnet with 3 wt% (Pr0.25Nd0.75)80Al20 as the additive inside the grain boundaries had better thermal stability than that of Nd-Fe-B magnet. The coercivity temperature coefficient β of Pr-Nd-Al Ce magnet was improved by 5.7%, and the irreversible loss of magnetic flux hirr was enhanced by 58% at the temperature of 100 ℃ compared with the Nd-Fe-B magnet. The improvement of thermal stability was attributed to the special sandwich-like structure consisting of two amorphous nonmagnetic phases sandwiching a layer of Re6(Fe, TM)11Al3 tetragonal phase, that compensated the coercivity of Ce magnets without critical elements.