摘要
In this study,we propose an approach of grain boundary modification that can significantly increase the coercivity of the B-lean Nd-Fe-B sintered magnets by intergranular addition of Nd-Ga.The coercivity is substantially enhanced from 1.51 to 2.04 T through optimizing the microstructure and adjusting the phase composition for the grain boundary phase in the annealed magnets.The matrix grains are covered by a continuous thin grain boundary phase accompanying the formation of intermetallic Nd_(6)Fe_(13)Ga phases.The analysis of magnetic behaviors above Curie temperature confirms that the grain boundary phase of annealed Nd-Ga doped magnets appears to be non-ferromagnetic,facilitating the intergrain exchange decoupling.Microstructure observation in grain boundary area indicates that some surface of the matrix grain is dissolved in the formation process of the Nd_(6)Fe_(13)Ga phase.It gives rise to a decrease in the proportion of matrix grains and saturation magnetization of the magnet.The detailed relationship between magnetic properties and microstructure is discussed based on these results.
基金
in part supported by Major Project of"Science and Technology Innovation 2025"in Ningbo(2018B10086)
Major project of"Inner Mongolia Science and Technology",Key Research and Development Program of Shandong Province(2019JZZY010321)
Zhejiang Province Public Welfare Technology Application Research Project(LGG21E010007)。
