Magnetization reversal mechanism for core-shell grains in GBD Nd-Fe-B sintered magnets based on in-situ domain observation
Magnetization reversal mechanism for core-shell grains in GBD Nd-Fe-B sintered magnets based on in-situ domain observation
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DOI：
10.1016/j.jallcom.2022.164414
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发表时间：
2022-06
影响因子：
6.2
通讯作者：
Yuqing Li;Dan Wu;Mingkun Wang;Zhanjia Wang;Weiqiang Liu;Yuan Teng;M. Yue;Hongguo Zhang;W. Xia
中科院分区：
文献类型：
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作者：
Yuqing Li;Dan Wu;Mingkun Wang;Zhanjia Wang;Weiqiang Liu;Yuan Teng;M. Yue;Hongguo Zhang;W. Xia
了解晶界扩散Nd-Fe-B磁体中形成核壳结构晶粒的磁化反转机理，可以进一步提高重稀土资源的利用效率，从而更有效地提高Nd-Fe-B烧结永磁体的矫顽力。本文对晶界扩散Nd-Fe-B磁体中核壳结构晶粒的磁畴结构及其动态演化进行了原位观察。在壳层区域，由于各向异性常数较高，饱和磁化强度较低，磁畴较宽。磁畴运动揭示了核壳结构的退磁过程是一个多步形核的过程。核壳结构晶粒的形核首先发生在核区，而在较大的反向场下，壳区的最外部分出现另一个反向形核。微磁学模拟结果证实了实验中观察到的形核和反转过程的可能性。研究结果有助于理解晶界扩散Nd-Fe-B烧结磁体的退磁过程和矫顽力提高机理。
Understanding the magnetization reversal mechanism of a core-shell structure grains formed in the grain boundary diffused Nd-Fe-B magnet can further improve the utilization efficiency of heavy rare earth resources to more effectively improve the coercivity of Nd-Fe-B sintered permanent magnet. In this paper, magnetic domain structure and its dynamic evolution of core-shell structural grains in grain-boundary-diffused Nd-Fe-B magnet were in-situ observed. Wider domains are found in shell regions due to higher anisotropy constant and lower saturation magnetization. The domain motion revealed that the demagnetization process of core-shell structure has a multi-step nucleation process. The nucleation of the core-shell structural grain firstly occurs at the core regions, while another reverse nucleation appears at the outmost portion in shell-region at a larger reverse field. The micromagnetic simulation results confirm the possibility of the nucleation and reversal process observed in the experiment. Our results can help understanding the demagnetization process and the coercivity enhancement mechanism of grain-boundary-diffused Nd-Fe-B sintered magnet.