强流脉冲电子束作用下Cu-Fe互不固溶体系扩散行为及合金化机制研究

Cu-Fe binary alloy has important theoretic research value and wild application prospect due to its high strength, excellent electrical conductivity and special magnetic property. However, elements Cu and Fe are difficult to realize solid solution because of the large positive heat of mixing. It is difficult to prepare these materials by using routine method. The metastable characteristics can be obtained on the bulk material surface by using high energetic beam surface modifications, where does not exist the consideration of adhesion strength inherent in the coating technologies. In view of this, this project is devoted to present a new route to achieve diffusion alloying between Cu and Fe by controlling surface microstructures, especially abundant crystal defect configuration by high current pulsed electron beam (HCPEB), in combination with heat treatment. In this project, the relationship between the defect structures and element diffusion behavior by systematically characterizing the microstructures on the irradiated surface will be established. Meanwhile, the diffusion alloying mechanism of Cu-Fe immiscible system after HCPEB treatment will be also explored. To reveal the mechanism of this above mentioned, it is important to study on the influence law of crystal defects type, distribution and density between HCPEB process. The dynamic analysis of diffusion alloying behavior between diffusion temperature, time and pressure are also investigated. Furthermore, the thermodynamic model of immiscible system alloying by HCPEB irradiation will be revised and established. This research can present significant technical supports for developing non-equilibrium mechanical alloying in immiscible system and new preparative technique for exploring immiscible alloys.

二元Cu-Fe合金具备高强度和优异的导电性以及特殊的磁性质，具有重要的理论研究价值和应用背景。但Cu-Fe之间生成热为正值且很难相容，常规方法制备这类材料较难。高能束表面改性可以在块体材料表面形成亚稳态，且无膜基结合问题。鉴于此，申请者提出利用强流脉冲电子束这一新的表面技术，通过控制辐照后材料表面的微观结构状态尤其是晶体缺陷组态，结合热处理，实现Cu-Fe互不固溶体系扩散合金化。本项目拟对辐照表面结构进行详细精确的表征，分析辐照缺陷和元素扩散之间的关系，揭示Cu-Fe互不固溶体系扩散合金化机制；研究辐照工艺对晶体缺陷种类、分布、密度等的影响规律；建立扩散温度、时间、压力等与扩散合金化行为的动力学关系；修正并建立强流脉冲电子束作用下互不固溶体系合金化热力学模型。本研究对发展非平衡态下的互不固溶合金化理论，开发新型互不固溶合金制备技术具有重要的指导意义。

采用强流脉冲电子束辐照技术对铜基及铝基二元互不相溶体系材料进行表面合金化，利用多种表征手段对辐照合金化后表层的微观结构状态进行精确表征，并且考察了强流脉冲电子束辐照合金化技术对机械性能和电化学性能的影响，总结和建立辐照合金化-微观结构-表面性能间的内在联系。.合金化诱发粉末冶金样品表面反复重熔，使合金化颗粒得到了显著细化，细化的合金化颗粒与Cu原子具有良好的界面结合。在辐照过程中，界面处元素获得足够的扩散驱动力发生扩散形成二元过饱和固溶体及长周期结构等。实验结果表明，合金化样品表层诱发形成的超细合金化颗粒、Cu亚晶和过饱和固溶体等结构起到弥散强化、亚晶强化和固溶强化的作用。此外，辐照样品也表现出了良好的减摩和耐磨性，这是细化的合金颗粒起到的阻隔冷焊、强化基体和促进机械摩擦层形成等作用极大地改善了材料表面的摩擦磨损性能。.Al基二元互不固溶体系表面合金化后，大量的合金化元素熔入基体形成合金化层，合金层厚度随着合金化次数的增加而增加。合金元素与Al基体间以一层较厚的非晶层相结合，金层中相结构主要由大量的金属间化合物、细小合金颗粒和固溶体构成。性能测试结果显示，合金化样品的耐腐蚀性均得到了显著的提高。表面熔坑密度的降低以及合金层中增强性离子的形成起到稳定表面连续而致密的钝化膜是腐蚀性能改善的关键性因素。.本研究对发展非平衡态下的互不固溶合金化理论，开发新型合金制备技术具有重要的指导意义。