热处理对烧结NdFeB磁体机械破碎磁粉的影响

将烧结ＮｄＦｅＢ磁体进行机械破碎，得到粒径大小适用于制备粘结磁体的磁粉，其矫顽力很低。在７００～１０５０℃的温度范围内进行热处理，实验结果表明：适当地选取热处理温度，可以显著地提高磁粉矫顽力，使其成为各向异性的高性能磁粉，用光学显微镜及ＳＥＭ对热处理前后磁粉的开矿进行了观察，未经热处理的机械破碎磁粉，颗粒边缘地区很细碎并且有很多裂纹，中心区域则相当寒带，热处理后，磁为分的边缘区域裂纹明显减少并趋于

Influence of Heat Treatment on the Coercivity and Morphology of the Magnet Powders Prepared by Mechanical Crushing Sintered NdFeB Magnets

Heat treatment experiments were carried out to magnet powders prepared by crushing the sintered NdFeB hard magnets, within the annealing temperature range from 700 to 1　050℃.The results have shown that the annealing treatment can effectively enhance the coercivity of the crushed powders,which is very low after the communition, to relative high values.The microstructural changes of the magnet powders during the annealing were checked using optical and scanning electronic microscopes. It is found out that the magnet powders have many cracks in their surface layer caused by the mechanical crush, while their center parts remain free from crack.On the other side, the magnet powders after annealing treatment possess have few cracks in the surface layer.This change is considered as the result of the repairing effect of the annealing treatment to the damaged surface,which should be the reason for the enhancement of the coercivity of the magnet powders.Meanwhile,in the powders after annealing, more Nd-rich particles can be observed evidently, some of which are determined as Nd-oxide. It indicates the ocurrence of oxidation is an other process happened during the annealing treatment,which should affect the recovery of the coercivity of the manget powders negatively.