摘要
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.
Influences of stacking fault energy （SFE） on the microstructures, tensile properties and fatigue behaviors of nanostrucmred （NS） Cu-A1 alloys prepared by severe plastic deformation （SPD） were systematically summerized. With the reduction of SFE, it is found that the dominant formation mechanism of nanostructures grad- ually transformed from the dislocation subdivision to the twin fragmentation and the grain sizes also decrease; while microstructural homogeneity is achieved more readily in the materials with either high or low SFE than in the materials with medium SFE. The strength of NS Cu-A1 significantly increases with decreasing the SFE, while there is an optimal SFE for the ductility of these materials. More significantly, the strength-ductility synergy of Cu- A1 alloys is prominently enhanced with reducing the SFE. Finally, simultaneous improvements of low-cycle fatigue and high-cycle fatigue properties ofNS Cu-Al alloys were achieved with decreasing the SFE. This can be attributed to the enhanced microstructure stability and the reduced strain localization in shear bands. With the reduction of SFE, the fatigue damage micro-mechanism was also transformed from grain boundary （GB） migration to other GB activities such as, atom shuffling, GB sliding and GB rotation.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期191-201,共11页
Acta Metallurgica Sinica
基金
国家自然科学基金项目50890173
50931005
51101162和51331007资助~~
关键词
纳米晶材料
层错能
微观结构
拉伸性能
疲劳性能中图法
nanostructured material, stacking fault energy, microstructure, tensile property, fatigue property
