本课题针对大尺寸稀有金属制品纯净度、组织和热应力控制难度大，热变形 后容易发生晶粒非均匀长大等问题，重点开展高纯稀有金属杂质元素走向及作用 规律、稀有金属烧结和形变过程中的组织演化规律及精确调控、超高纯钨及钨合 金靶材晶粒长大机理及晶粒尺寸控制等重大科学问题的研究。采用三维原子探针 和透射电镜原位拉伸等技术揭示杂质种类、含量和分布及其对高纯稀有金属材料 组织性能的影响规律，揭示高纯稀有金属材料在粉末制备与处理、压制、烧结和 变形加工及其后续处理过程中杂质元素的存在形式、走向、各杂质元素间的耦合 效应及其作用规律；阐明稀有金属材料烧结致密化规律与组织精确调控原理，掌 握大尺寸高纯稀有金属制品高温高压烧结过程中形状尺寸精度控制的关键因素； 掌握高纯稀有金属材料塑性变形过程中的组织演化规律与控制方法，建立成分工艺-组织-综合性能之间的关系。

This topic aims at the difficulty of controlling the purity, structure and thermal stress of large-size rare metal products, and the uneven growth of crystal grains after thermal deformation. The focus is on the trend and action law of high-purity rare metal impurity elements, and the sintering and sintering of rare metals. Research on major scientific issues such as the law of microstructure evolution and precise control during deformation, the mechanism of grain growth of ultra-high purity tungsten and tungsten alloy targets, and the control of grain size. Three-dimensional atom probe and transmission electron microscopy in-situ stretching techniques are used to reveal the types, content and distribution of impurities and their influence on the microstructure and properties of high-purity rare metal materials, and reveal the use of high-purity rare metal materials in powder preparation and processing, pressing, and sintering. The existence form and direction of impurity elements, the coupling effect between impurity elements and their action laws in the process of deformation and deformation processing and subsequent processing; clarify the sintering densification law of rare metal materials and the principle of precise control of the structure, and master large-scale high-purity rare metals The key factors for the shape and size accuracy control during the high temperature and high pressure sintering process of the product; master the structure evolution law and control method in the plastic deformation process of high-purity rare metal materials, and establish the relationship between composition process-structure-comprehensive performance.