预低周疲劳变形对金属单晶体静态力学行为影响的机理性研究

项目名称： 预低周疲劳变形对金属单晶体静态力学行为影响的机理性研究

项目编号： No.51271054

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 李小武

作者单位： 东北大学

项目金额： 80万元

中文摘要： 本项目拟采用不同取向Cu单晶体、低层错能Cu-16at.%Al合金单晶体以及含析出相的双相Al-4wt.%Cu合金单晶体等fcc晶体作为研究材料，在一定塑性应变幅范围内对其进行不同程度的（即不同累积塑性应变量）预疲劳变形试验后，再在一定应变速率下进行单向拉伸得到它们的基本静态力学性能数据。利用光学显微镜、扫描电镜电子通道衬度技术和透射电镜等观察分析预疲劳变形后的变形（损伤）特征、位错结构以及预疲劳后拉伸变形特征、断口形貌特征和位错结构的变化，通过与直接拉伸变形的相应结果进行系统比较，进而清晰地揭示预疲劳变形对fcc金属晶体静态力学行为影响的一般性规律与微观机理，重点考察晶体取向、层错能和沉淀相等因素对机理的具体影响。该工作对深入认识金属晶体的低周疲劳锻炼强化机制及其在疲劳损伤后静态力学性能下降的微观机理具有重要的理论和实际指导意义，并且可为金属晶体疲劳损伤后剩余疲劳寿命预测提供有益的参考。

中文关键词： 金属晶体；低周预疲劳；静态力学行为；疲劳损伤；微观机理

英文摘要： Several kinds of typical face centered cubic (fcc) metallic crystals, including Cu single crystals with different orientations, Cu-161t.%Al alloy single crystals with low stacking fault energy, Al-4wt.%Cu alloy single crystals containing precipitates, etc. are selected as the target materials in the present research project. Firstly, fatigue pre-deformation to different stages (i.e. to different accumulative plastic strains) are performed on these single crystals within a certain range of plastic strain amplitudes, and uniaxially tensile deformation tests are subsequently carried out on these pre-fatigued crystals at a fixed strain rate to obtain the basic data of their static mechanical properties. Optical microscope, the electron channeling contrast (ECC) technique in scanning electron microscopy (SEM) together with transmission electron microscopy (TEM) are adopted to observe fatigue deformation characteristics and fatigue dislocation structures, as well as tensile deformation features, fracture surface morphologies and corresponding dislocation structures of pre-fatigued crystals. By making comparisons to the experimental data obtained from direct tensile deformation tests of these single crystals, the micro-mechanisms for the effect of fatigue pre-deformation on the static mechanical behavior of fcc metalli

英文关键词： Metallic crystals；Low-cycle pre-faigue；Static mechanical behavior；Fatigue damage；Micromechanism