Thermal instability problems of nanostructured materials, including grain coarsening and recrystallization, can be alleviated by introducing nanoscale coherent twin boundary (CTB) structures. However, the detailed interaction mechanism between CTB and grain boundaries (GBs) during microstructural transformation has not been well elucidated. To gain insight, we investigate the migration behavior of CTB-intercepted GBs in twinned copper nanowires at elevated temperatures through transmission electron microscopic observations and molecular dynamics simulations. The results show that numerous partial dislocations are conveyed to the CTB-intercepted GB through the densely distributed CTBs and further transferred to the nanowire surface along the GB. The growth of the twinned region along the diminishing GB is driven by minimizing the excess energy stored in dislocation defects and GBs. This CTB-mediated GB migration in twinned copper nanowires can be deactivated by surface passivation. This study will help to elucidate how the thermal stability of nanostructured metals is influenced by the twin structure and surface passivation.

中文翻译：

---

增强孪生铜纳米线热稳定性的机理理解

纳米结构材料的热不稳定性问题，包括晶粒粗化和再结晶，可以通过引入纳米级共格孪晶边界（CTB）结构来缓解。然而，微观结构转变过程中 CTB 和晶界 (GB) 之间的详细相互作用机制尚未得到很好的阐明。为了获得洞察力，我们通过透射电子显微镜观察和分子动力学模拟研究了在高温下孪生铜纳米线中 CTB 拦截的 GB 的迁移行为。结果表明，大量的部分位错通过密集分布的CTB传递到CTB拦截的GB，并进一步沿着GB转移到纳米线表面。孪生区域沿着逐渐缩小的晶界的生长是通过最小化位错缺陷和晶界中存储的多余能量来驱动的。这种 CTB 介导的孪晶铜纳米线中的 GB 迁移可以通过表面钝化来失活。这项研究将有助于阐明纳米结构金属的热稳定性如何受到孪晶结构和表面钝化的影响。