论文部分内容阅读
总结了层错能对Cu-Al纳米晶合金微观结构、拉伸性能和疲劳行为的影响.研究表明:随着层错能的降低,材料微观结构的演化逐步从位错分割机制主导转变为孪晶碎化机制主导,导致其平均晶粒尺寸逐步减小,而其均匀微观结构的形成经历先难后易的转变.同时,发现Cu-Al纳米晶合金的强度随层错能的降低得到明显改善,其均匀延伸率存在一最优值,使其均匀延伸率最佳.对不同晶粒尺寸的样品进行力学实验证实,随层错能降低,其强塑性匹配得到明显提升.在循环变形过程中,随层错能降低,晶粒长大导致的微观组织不稳定性和高度应变局部化的剪切带均有明显改善.材料的疲劳损伤微观机制随之从晶界迁移主导的晶粒长大逐步转变为其它晶界行为,如原子重组、晶界滑动和转动等.纳米材料的综合疲劳性能(低周和高周疲劳)随层错能的降低呈现同步提高的趋势.
The effects of stacking faults on the microstructures, tensile properties and fatigue behavior of Cu-Al nanocrystalline alloys are summarized.The results show that the evolution of the microstructures gradually changes from dislocation splitting mechanism to twinning as the stacking fault energy decreases The results show that the average grain size of the Cu-Al nanocrystalline alloy decreases with the decrease of the stacking fault energy, and the formation of uniform microstructure undergoes the transition from the first to the easiest. Improve the uniform elongation of an optimal value, so that the uniform elongation of the best for different grain size samples tested by mechanical experiments, with the stacking fault can be reduced, the strong plastic matching has been significantly improved in the cyclic deformation process , The microstructure instability caused by grain growth and the shear band localized by high strain are all improved obviously with the decrease of the stacking faults.The microscopic mechanism of fatigue damage of the material followed by the migration of the grain length Large gradually into other grain boundary behavior, such as atomic recombination, grain boundary sliding and rotation, etc. The comprehensive fatigue properties (low cycle and high cycle fatigue) of nanomaterials show a synchronous increase with the decrease of the layer fault energy.