界面-孔洞交互作用下多晶钛铝基合金微观塑性变形行为的原子模拟

项目名称： 界面-孔洞交互作用下多晶钛铝基合金微观塑性变形行为的原子模拟

项目编号： No.51201147

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 金属材料学科

项目作者： 赵文娟

作者单位： 湘潭大学

项目金额： 25万元

中文摘要： 计算机辅助的材料设计有助于从微观层次深入理解显微组织结构，特别是位错、界面、孔洞等缺陷结构，对金属材料力学性能和塑性变形行为的影响机制；尤其是原子尺度的模拟可以再现某些实验难以观测到的过程，且高效便捷。片层组织是TiAl基合金的典型微观组织结构之一，片层组织中存在着的复杂界面对其塑性变形影响很大。孔洞是影响金属结构材料服役性能的另一种典型缺陷，且易于在界面及其附近萌生。本研究采用分子动力学方法模拟含微孔洞的TiAl基多晶体系的塑性变形，研究变形中的位错组态及其演化动力学，分析应力载荷作用下多晶界面处的位错形核扩展、界面转动（迁移）等力学行为；明确界面取向等结构参数与力学性能间的本构关系；揭示孔洞位置及其与界面的间距对体系位错组态及力学行为的影响规律；探索服役条件下界面、孔洞与材料性能的动态耦合响应机制，为改善力学性能的微观组织优化设计提供方向性指导。

中文关键词： 界面；孔洞；分子动力学；塑性变形；钛铝基合金

英文摘要： Microstructures, particularly some defects like dislocations, interfaces and voids et al., have decisive effect on the mechanical properties and deformation mechanisms of metallic materials, which is one of the most important areas of investigations in material science. Material computation contributes to penetration insight into the deformation mechanisms, especially for the processes that incapable or hardly reachable experimentally. In the meanwhile, it exhibits a combination of high efficiency and convenience. Lamellar structure is a typical microstructure in TiAl-based alloys, in which different grain boundaries and inter-phase interfaces with complex orientations exist. The co-existence of these complex interfaces has duplex effects on the mechanical properties. On the other hand, the fracture process of metallic materials affected by void growth and coalescence directly, and this is one of the most important reasons for material damage. Moreover, void nucleation easily initiates on or in the vicinity of interfaces. Employing molecular dynamics method, the present study discusses two important issues, the effect of interfaces and voids on the plastic deformation mechanisms and the mechanical properties of TiAl-based alloys. By building a series of polycrystalline simulation boxes, the dynamic evolutionary

英文关键词： interface；void；molecular dynamics；plastic deformation；TiAl-based alloy