聚结(物理)
材料科学
纳米孔
成核
位错
铜
纳米孔
散射
凝聚态物理
复合材料
纳米技术
冶金
光学
化学
物理
天体生物学
有机化学
作者
Wenbo Bi,Y. F. Wang,Xingming Zhang,Lei Deng,Jianfeng Tang,Feng Zhao,L. Wang
摘要
We systematically study the low cycle fatigue behavior and its dependence of specific surface area (ζ) for nanoporous copper (NPC) under ultrahigh strain rate (γ˙≈109 s−1) cyclic shear loading by conducting large-scale molecular dynamic simulation and small-angle x-ray scattering analysis. With an increase in ζ, NPC undergoes a transition from the first excellent anti-fatigue property (ζ<1.24nm−1) to the subsequent easy-to-fatigue capacity (ζ≥1.24nm−1). Two different mechanisms are governing fatigue: (i) smooth nucleation and propagation of dislocations for the former and (ii) nanopore compaction/coalescence for the latter by prohibiting the activities of dislocations. For NPC with ζ=0.42nm−1, fatigue contributes to a surprising superelasticity, prompted by the entanglements and reversed disentanglements of longer dislocations. Surface reconstruction contributes to the fatigue tolerance of NPC by facilitating local surface roughening and the emission of dislocation slips, and it becomes more pronounced with decreasing ζ.
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