激光微熔-喷丸诱导纳米颗粒增强细晶复合层形成机理与强化机制

Failure of metal components often occurs due to surface damage, severely restricting their engineering applications. Therefore, the improvement of the surface performances becomes one of the key issues to be solved urgently in the manufacture of components. The project intends to conduct the research on fabrication of nanoparticle reinforced fine-grained composite layer using the hybrid process combining laser micromelting and laser peening, exploring the new method of surface nanocomposite strengthening. The movement embedding process of nanoparticles and coupled response law of substrate induced by laser micromelting-peening are systematically investigated. And the influence laws of process parameters on the microstructure, surface integrity and performance of nanoparticle reinforced composite layer are analyzed under the thermal-mechanical hybrid condition. The dynamic bonding model between nanoparticles and substrate and the relational model of process - stress/structure - performance are established, and the interfacial bonding mechanism and grain refinement mechanism are ascertained, subsequently the microscopic formation mechanism of the nanoparticle reinforced fine-grained surface composite layer is revealed, and the collaborative strengthening mechanism based on the composite microstructure and residual stress is illuminated. The preparation process guideline of nanoparticle reinforced fine-grained composite layer is obtained. The process optimization, stress/structure control and performance enhancement of the composite layer are achieved. The research of this project will not only enrich and develop the surface strengthening methods and basic theories of metal components, but also have an important engineering significance to explore and develop the high-performance nanoparticle reinforced surface composite layer.

金属结构件常因表面损伤而发生失效，严重制约其工程应用，因此，提高表面性能成为结构件制造中亟需解决的关键问题之一。本项目拟开展采用激光微熔与激光喷丸相结合的处理方法制备纳米颗粒增强细晶复合层的研究，探索表面纳米复合强化新方法。系统研究激光微熔-喷丸诱导纳米颗粒运动嵌入过程与基体的耦合响应规律，分析热-力复合条件下工艺参数对纳米颗粒增强复合层微观结构、表面完整性和性能的影响规律，建立纳米颗粒与基体的动态结合模型及工艺-应力/结构-性能关系模型，探明界面结合机制和晶粒细化机制，揭示激光微熔-喷丸诱导纳米颗粒增强细晶表面复合层形成的微观机理，阐明基于复合微结构和残余应力的协同强化机制，获得纳米颗粒增强细晶复合层制备工艺准则，实现复合层工艺优化、应力/结构调控和性能增强。本项目研究不仅能够丰富和发展金属构件表面强化方法和基础理论，而且对探索开发高性能纳米颗粒增强表面复合层具有重要工程意义。

针对金属结构件常因表面损伤而发生的失效，本项目采用激光微熔与激光喷丸相结合的处理方法制备纳米颗粒增强细晶复合层，探索表面复合强化新方法。基于有限元模拟、微观组织和性能分析，研究了激光微熔诱导纳米颗粒运动嵌入过程与基体的耦合响应规律，分析了激光微熔工艺参数对纳米颗粒增强层微观结构和性能的影响规律，建立了纳米颗粒与基体的动态结合模型；模拟研究了激光微熔微气孔和增强颗粒对激光冲击的影响，揭示了残余应力分布规律，阐明了激光微熔-喷丸诱导纳米颗粒增强细晶表面复合层形成的微观机理；模拟和实验研究了激光冲击植入纳米颗粒的微观结构和表面性能，推导出激光冲击波诱导纳米颗粒运动速度和激光冲击植入纳米颗粒嵌入深度模型，探明了纳米颗粒-基体结合机制和基体晶粒细化机制，揭示了基于复合微结构和残余应力的协同强化机制，实现了增强层工艺优化、应力/结构调控和性能增强。本项目按计划完成了预期研究目标，研究成果将为探索开发高性能纳米颗粒增强表面复合层提供重要理论依据和参考。