Micromagnetic simulation of the influence of grain boundary on cerium substituted Nd-Fe-B magnets

摘要

A three-dimensional finite element model was performed to study the magnetization reversal of (Ce_xNd_1-x)₂Fe₁₄B nanocomposite permanent magnets. The influences of volume fraction, width and performance parameters of the grain boundary (GB) composition on the coercivity were analyzed by the method of micromagnetic simulation. The calculation results indicate that the structure and chemistry of GB phase play important roles in Nd₂Fe₁₄B-based magnets. An abnormal increase in the value of coercivity is found to be connected with the GB phase, approximately when the percentage of doped cerium is between 20% and 30%. While the coercivity decreases directly with the increase in cerium content instead of being abnormal when there is no GB phase in magnets at all or the value of magnetocrystalline anisotropy or exchange integral is too large.