烧结NdFeB磁体热压变形后富Nd相的显微组织

摘要

采用热压变形法对NdFeB磁体晶间富Nd相的显微组织进行了研究。实验结果表明， NdFeB磁体经真空热压变形后， 富Nd相不再平均地分布在磁体晶间，而是聚集成团块状或从磁体边缘渗出。 显微组织分析表明， 富Nd相主要是由α-Nd和Nd2Fe17两相组成，与Nd-Fe合金的共晶组织成分接近 对于晶间添加Al元素的磁体，Al溶入晶间形成Nd2Fe15Al2相弥散地分布在晶界上， 这有益于磁体矫顽力的提高；对于晶间添加Cu元素的磁体， 晶间没有发现有新相产生%The microstructure of intergranular Nd-rich phase of sintered NdFeB magnets has been studied by means of thermal extruding. After thermal extruding Nd2Fe17B7 magnets， Nd-rich phases are not distributed in the intergranular region on the average and a lot of Nd-rich phases aggregate or separate from the magnet. The results show that the microstructure of Nd-rich is consisted of α-Nd phase and Nd2Fe17 phase， which approaches to eutectic structure of binary Nd-Fe alloy. After adding element Al， Nd2Fe15Al2 phases segregate near to the grain boundary of the magnetic Nd2Fe14B phase, which leads to the improvement of coercivity of magnets.