典型FCC金属中低Σ取向晶界切应力作用下力学行为的研究

项目名称： 典型FCC金属中低Σ取向晶界切应力作用下力学行为的研究

项目编号： No.51201127

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： 万亮

作者单位： 西安交通大学

项目金额： 25万元

中文摘要： 本项目拟采用计算机原子尺度模拟方法，结合原位透射电镜等实验手段，选取典型面心立方金属铜、铝和镍中低重位数Σ取向与近Σ取向的对称倾斜、非对称倾斜以及扭转晶界为研究对象，考察它们在不同取向切应力与温度下的力学行为与结构演化方式，同时结合晶界的各种结构模型，探讨这些晶界的"结构-力学行为"规律。研究工作致力于澄清如下问题：1）对于所选晶界，在不同取向切应力与温度下，其结构演化方式是否符合晶界重位点阵理论所预测的晶界DSC位错运动机制描述？2）对于特定材料（铜、铝和镍）中的晶界，其发生晶界滑移迁移耦合运动需要什么内部（晶界的几何取向）与外部（切应力与温度）条件？3）不同材料（铜、铝和镍）中相同几何取向的晶界其力学行为会有什么不同表现形式？预期通过本项目的研究工作可望促进对金属多晶体材料力学行为中晶界效应更深层次的认识，并为解释当前实验中所发现的金属纳米晶材料冷态形变条件下的晶粒生长现象提供线索。

中文关键词： 多晶体材料；晶界；晶界迁移；双晶晶体学；孪晶

英文摘要： We plan to study the shear response of some particular grain boundaries (GBs) in typical FCC metals Cu, Al and Ni by computer atomistic simulation methods combined with in-situ transmission electron microscopy experimental techniques. Three types of GBs including the symmetric tilt, asymmetric tilt and pure twist boundaries with their misorientations corresponding to the low Σ values and the vicinal boundaries are selected for the study. Shear of these GBs along different directions and at different temperatures will be performed. With a detailed analysis of the stress-strain response and structure evolution behavior of these GBs, the "structure - mechanical behavior" relationship of these GBs can be explored based on the existing structure models for GBs. In particular, the study will focus on the clarification of the following questions. 1) For shear of the selected GBs along different directions and at various loading temperatures, can the structure evolution behavior of these GBs be described by the GB DSC (Displacement Shift Complete) dislocation mechanism? 2) For GBs in a particular kind of material (Cu, Al and Ni), what are the intrinsic conditions (geometry of GBs) and extrinsic conditions (shear stress and loading temperature) for the activation of GB sliding-migration coupling motion? 3) How can GBs wi

英文关键词： polycrystalline materials；grain boundary；grain boundary migration；bi-crystallographic lattice；twin