热变形磁体力学性能的各向异性和晶界强韧化研究

项目名称： 热变形磁体力学性能的各向异性和晶界强韧化研究

项目编号： No.51501213

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 一般工业技术

项目作者： 尹文宗

作者单位： 中国科学院宁波材料技术与工程研究所

项目金额： 21万元

中文摘要： 钕铁硼热变形磁体具有磁能密度高、制备流程短、易于实现近终成型等优点，目前已被应用于汽车EPS电机、空调压缩机的IPM电机等方面。但热变形磁体的片状晶堆垛结构和晶界各向异性造成其力学性能呈现明显的各向异性，从而导致沿平行于片状晶方向的力学性能很差，并使其在后续机加工和使役过程中极易沿平行于片状晶方向的晶界(简称平行晶界)开裂和破碎。为此，本项目围绕改善热变形磁体内平行晶界的强韧性，采用在平行晶界中富集韧性纳米沉淀相和弥散分布金属塑性颗粒两种方法来改善平行晶界的力学性能，达到抑制裂纹沿平行晶界扩展或改变裂纹扩展方向的目的，进而提高磁体沿平行片状晶方向的力学性能。与此同时，阐述力学性能的各向异性和断裂机制对微观组织结构的依赖关系，深入研究平行晶界中纳米沉淀相和金属颗粒与基体相(Nd2Fe14B相和晶界富钕相)之间的晶格匹配关系和界面结合强度，为寻找合适的增韧相和增韧方法提供理论指导。

中文关键词： 热变形钕铁硼；力学性能；晶界；增韧

英文摘要： Hot-deformed (HD) Nd-Fe-B magnet has several advantages, such as high magnetic flux, facile preparation, near-net-shape production, etc.. So far it has been used in EPS motors for cars and IPM motors for compresser in air-conditioner. HD Nd-Fe-B magnet has the characteristics of both laminated structure consisted of Nd2Fe14B platelets and anisotropic grain boundary (GB). They collaborate to determine the strong anisotropy of mechanical performance and thus the poor mechanical performance along the direction parallel to Nd2Fe14B platelets in HD Nd-Fe-B magnet. As a result, HD Nd-Fe-B magnets are easily cracked or broken along the GB parallel to Nd2Fe14B platelets (GB-P). To improve the strength and toughness of GB-P, two methods will be carried out in this project: the aggregation of nano-sized ductile precipitates in GB-P and the dispersion of metal particles at GB-P. Both the two methods will inhibit the crack propagation or change the path of crack propagation in GB-P, which could improve the mechanical performance along the direction parallel to Nd2Fe14B platelets for HD Nd-Fe-B magnet. Meanwhile, the dependence of the anisotropy of mechanical performance and fracture mechanisms on the phases and microstructures will be revealed. Further investigation will be carried out on the lattice structure and the bonding strength of the interfaces between ductile precipitates (or metal particles) and Nd2Fe14B phase (or Nd-rich phase). Such investigation on the interface will accelerate the search for suitable ductile phases as well as the methods for introducing them into HD Nd-Fe-B magnets.

英文关键词： hot-deformed Nd-Fe-B;mechanical performance;grain boundary;toughening