Slip-activated surface creep with room-temperature super-elongation in metallic nanocrystals.
Slip-activated surface creep with room-temperature super-elongation in metallic nanocrystals.
复制标题
DOI：
10.1038/nmat4813
复制
发表时间：
2017-04
期刊：
影响因子：
41.2
通讯作者：
L. Zhong;F. Sansoz;Yang He;Chongmin Wang;Ze Zhang;S. Mao
中科院分区：
文献类型：
--
作者：
L. Zhong;F. Sansoz;Yang He;Chongmin Wang;Ze Zhang;S. Mao
纳米级的金属晶体已被证明遵循“越小越强”的趋势。然而，由于有限来源的晶体滑移导致的早期塑性失稳，它们通常具有较低的延性。在这里，通过在原子尺度的电子显微镜下的表现，我们报告了面心立方银纳米晶体的不寻常的室温超伸长而没有软化，其中晶体滑移是表面扩散蠕变的刺激。这种相互作用的机制在实验和理论上分别通过表面扩散蠕变和位错塑性来控制纳米晶体的塑性变形，该机制分别通过表面扩散蠕变和位错塑性控制纳米晶体稳定的下限和上限之间的与材料有关的样品直径范围内的纳米晶体的塑性变形，远远超出纯扩散中介变形的最大尺寸(例如Coble型蠕变)。这项工作深入了解了原子尺度的扩散-位移耦合变形机制，同时最大化了纳米材料的延展性和强度。
Nanoscale metallic crystals have been shown to follow a ‘smaller is stronger’ trend. However, they usually suffer from low ductility due to premature plastic instability by source-limited crystal slip. Here, by performingin situatomic-scale transmission electron microscopy, we report unusual room-temperature super-elongation without softening in face-centred-cubic silver nanocrystals, where crystal slip serves as a stimulus to surface diffusional creep. This interplay mechanism is shown experimentally and theoretically to govern the plastic deformation of nanocrystals over a material-dependent sample diameter range between the lower and upper limits for nanocrystal stability by surface diffusional creep and dislocation plasticity, respectively, which extends far beyond the maximum size for pure diffusion-mediated deformation (for example, Coble-type creep). This work provides insight into the atomic-scale coupled diffusive–displacive deformation mechanisms, maximizing ductility and strength simultaneously in nanoscale materials.