梯度纳米结构铜应变控制疲劳机制研究

项目名称： 梯度纳米结构铜应变控制疲劳机制研究

项目编号： No.51471172

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 卢磊

作者单位： 中国科学院金属研究所

项目金额： 85万元

中文摘要： 材料结构件的疲劳损伤往往始于表面，表面结构设计和改性是提高材料疲劳性能的常用方法。近年来，表层梯度纳米结构被证明能同时提高材料强度和疲劳寿命，但对其疲劳机理和抗疲劳损伤能力的来源尚缺乏系统研究和深入理解。本项目拟利用表面机械研磨处理技术在纯铜和铜合金棒表层加工梯度纳米结构层，并通过应变幅控制的拉压疲劳实验和微观结构表征系统研究梯度纳米结构金属在疲劳过程中的循环硬化/软化行为、微观结构演化以及疲劳裂纹萌生过程，阐明梯度纳米结构的微观结构特征和热稳定性与疲劳性能和损伤机理的相互关系，为设计疲劳性能优异的工程金属材料提供实验和理论依据。

中文关键词： 疲劳断裂；循环变形；微观组织；梯度结构；结构稳定性

英文摘要： Fatigue failure of material components always initiates at the surfaces; microstructure modification to enhance surface properties is uaually utilized to increase the fatigue performance of materials. It is established recently that introduction of surface gradient nano-grained structure brings about enhancements in strength and fatigue life; however, there is still lack of systematical investigation and understanding on the fatigue mechanism and the origin of fatigue damage-tolerance in the gradient nano-grained structure. In this project, pure copper and copper alloy cylinders with surface gradient nano-grained structure are fabricated by means of a surface mechanical grinding treatment; and through strain amplitude-controlled tension-compression fatigue testing and microstructural characterization, we will reveal the cyclic hardening/softening behavior, microstructural evolution the fatigue crack nucleation process in the cyclically deformed gradient nano-grained structure. The contribution of the microstructural characteristics and thermal stability to the fatigue performance and damage nucleation mechanism will be established, which may provide experimental and theoretical guide for designing engineering structural materials with optimized fatigue performance.

英文关键词： Fagitue fracture;Cyclic deformation;Microstructure;gradient structure;microstructure stability