轻合金热/力耦合植入颗粒型纳米薄膜的可控制备及协同强化机制

The engineering application of light alloys is limited for their low intensity, low hardness and poor wear performance, so it is urgent to improve their surface mechanical property in the manufacturing process of structural components. .In this proposal, a novel fabrication method of carbon-based nanofilm is proposed to improve surface mechanical properties of light alloys, which is realized by implanting WC or SiC nanoparticles into the surface of light alloys through laser shock peening under dynamic strain aging temperature (so-called coupled thermo-force effects). .To achieve the fabrication principles of carbon-based nanofilm and clarify its collaborative strengthening mechanism, some important fundamental issues are addressed in this proposal. The first is to investigate the effects of processing parameters on the surface integrity and mechanical properties including friction, wear properties, and high temperature fatigue performance of carbon-based nanofilm. The second is to analyze the diffusion behavior of nanoparticles and dislocation motion, and their coupling interactions process. The third is to develop the stress-strain constitutive relation and strong correlations between the preparation parameters, microstructure and mechanical performance in system. The last is to investigate the microstructural evolution of the nanofilm along the depth direction. As a result, the structural elements and properties of carbon-based nanofilm can be predicted and controlled. .The above researches involve many new scientific issues, and these research achievements can not only enrich and develop the surface modification technology and basic theory of light alloys, but also open up a new avenue for their large-scale industrial applications.

轻合金由于表面强度和硬度较低、耐磨性能差，严重阻碍了其工程应用，提高轻合金的表面性能成为结构件制造中的关键问题之一。本项目拟开展动态应变时效温度下激光喷丸(热/力耦合)植入颗粒型轻合金纳米薄膜的制备理论及协同强化机制研究，探索提高轻合金表面力学性能的方法。系统研究热/力耦合条件下工艺参数对植入颗粒型纳米薄膜的表面完整性、摩擦磨损性能和高温疲劳性能的影响规律，分析纳米颗粒扩散行为、位错运动以及耦合作用过程，建立轻合金应力-应变本构关系及工艺参数-微观结构-宏观性能的强关联关系，阐明深度方向的微观结构演变规律，获得碳基纳米薄膜制备工艺准则，揭示热/力耦合作用下纳米薄膜的协同强化机制，实现轻合金热/力耦合植入颗粒型纳米薄膜结构和功能的预测与控制。相关研究内容涉及众多全新科学问题，其研究成果可以丰富和发展轻合金表面改性基础理论和技术，为轻合金大规模的工业应用开辟一条新的道路。

本项目拟开展动态应变时效温度下激光喷丸(热/力耦合)植入颗粒型轻合金纳米薄膜的制备理论及协同强化机制研究，探索提高轻合金表面力学性能的方法，项目主要取得了以下进展：① 建立轻合金热/力耦合植入颗粒型纳米薄膜制备工艺，获得典型材料碳基纳米薄膜的表面完整性、微观组织结构和力学性能的基本数据；② 建立典型材料薄膜制备的工艺参数-微观结构-宏观性能之间的强关联关系，获得热/力耦合的纳米薄膜制备工艺准则；③模拟和分析纳米颗粒的扩散行为以及位错运动，揭示颗粒扩散和位错运动耦合作用过程，在纳米颗粒碰撞过程中的速度传递的基础上，获得了第二次激光冲击植入纳米颗粒深度模型，从而推导了二次激光冲击植入纳米颗粒深度模型；④研究不同温度、不同冲击层数对合金表面纳米化/非晶化的影响，揭示热/力耦合植入颗粒轻合金表层原位纳米化机理; ⑤建立碳基纳米薄膜强化效果的关系模型，推导三种强化方式的综合表达式，并计算每种强化方式对强化效果的贡献值，揭示纳米薄膜的协同强化机制。.在项目执行期内，圆满完成计划任务书的各项任务。研究成果获2013年江苏省科学技术奖一等奖1项，出版英文专著《Laser Shock Processing of FCC Metals: Mechanical Properties and Micro-Structural Strengthening Mechanism》和中文专著《激光冲击波强化技术及微观塑性变形机制》2部，发表论文10篇，其中SCI收录7篇，EI收录3篇(不含SCI收录)。项目主要研究内容纳米颗粒激光冲击波植入工艺、宏观性能和协同强化机制的论文已投稿金属材料TOP1期刊《Acta Materialia》，目前正在审稿中；有关多次冲击纳米颗粒植入深度模型与计算的数据准备投稿二区物理期刊《Journal of Physics D: Applied Physics》。获授权发明专利2件，申请中国发明专利1件、PCT国际发明专利(已进入美国)1件。参加国际/国内会议交流16人次，做分组报告3次。研究执行期内，项目组负责人和主要成员晋升教授2名，培养博士研究生1名、硕士研究生3名。