Effect of microstructure on the coercivity of HDDR Nd-Fe-B permanent magnetic alloy  

作　　者：LIU Min SUN Yan HAN GuangBing YANG Wu GAO RuWei 

机构地区：[1]School of Physics,Shandong University,Jinan 250100,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2008年第10期1557-1564,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 50671055)

摘　　要：The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations of the structure defect factors based on the nucleation and pinning mechanism with 2r0/lex (where r0 and lex are the defect thickness and the length of exchange coupling, respec-tively) were calculated. The results show that the coercivity mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary. For a fixed lex, when 2r0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r0/lex = 1.67. The calcula-tion result is consistent well with the experimental result given by Morimoto et al.The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations of the structure defect factors based on the nucleation and pinning mechanism with 2r 0/lex (where r 0 and lex are the defect thickness and the length of exchange coupling, respectively) were calculated. The results show that the coercivity mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary. For a fixed lex, when 2r 0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r 0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r 0/lex = 1.67. The calculation result is consistent well with the experimental result given by Morimoto et al.

关 键 词：HDDR process ANISOTROPY COERCIVITY structure DEFECT EXCHANGE COUPLING interaction 

分 类 号：O482.5[理学—固体物理]