Zhu Ting, Li Ju, Samanta Amit, Kim Hyoung Gyu, Suresh Subra
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Proc Natl Acad Sci U S A. 2007 Feb 27;104(9):3031-6. doi: 10.1073/pnas.0611097104. Epub 2007 Feb 21.
Nano-twinned copper exhibits an unusual combination of ultrahigh strength and high ductility, along with increased strain-rate sensitivity. We develop a mechanistic framework for predicting the rate sensitivity and elucidating the origin of ductility in terms of the interactions of dislocations with interfaces. Using atomistic reaction pathway calculations, we show that slip transfer reactions mediated by twin boundary are the rate-controlling mechanisms of plastic flow. We attribute the relatively high ductility of nano-twinned copper to the hardening of twin boundaries as they gradually lose coherency during plastic deformation. These findings provide insights into the possible means of optimizing strength and ductility through interfacial engineering.
纳米孪晶铜展现出超高强度与高延展性的异常组合，同时应变率敏感性也有所增加。我们构建了一个机理框架，用于预测速率敏感性并从位错与界面的相互作用角度阐明延展性的起源。通过原子反应路径计算，我们表明由孪晶界介导的滑移转移反应是塑性流动的速率控制机制。我们将纳米孪晶铜相对较高的延展性归因于孪晶界在塑性变形过程中逐渐失去共格性时的强化作用。这些发现为通过界面工程优化强度和延展性的可能方法提供了见解。
