Division of Engineering and Applied Science, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USA.
Small. 2014 Jan 15;10(1):100-8. doi: 10.1002/smll.201301060. Epub 2013 Jul 19.
Room-temperature uniaxial compressions of 900-nm-diameter aluminum bi-crystals, each containing a high-angle grain boundary with a plane normal inclined at 24° to the loading direction, revealed frictional sliding along the boundary plane to be the dominant deformation mechanism. The top crystallite sheared off as a single unit in the course of compression instead of crystallographic slip and extensive dislocation activity, as would be expected. Compressive stress strain data of deforming nano bicrystals was continuous, in contrast to single crystalline nano structures that show a stochastic stress strain signature, and displayed a peak in stress at the elastic limit of ~ 176 MPa followed by gradual softening and a plateau centered around ~ 125 MPa. An energetics-based physical model, which may explain observed room-temperature grain boundary sliding, in presented, and observations are discussed within the framework of crystalline nano-plasticity and defect microstructure evolution.
900nm 直径的铝双晶在室温下进行单轴压缩实验，每个双晶都含有一个与加载方向成 24°夹角的高角度晶界，实验揭示晶界的摩擦滑动是主要的变形机制。在压缩过程中，上部分晶体作为一个整体而非预期的通过晶体滑移和大量位错运动而被剪切。与表现出随机应力-应变特征的单晶纳米结构不同，纳米双晶体的压缩应力-应变数据是连续的，在弹性极限约 176MPa 处表现出应力峰值，随后逐渐软化，并在约 125MPa 处出现一个平台。本文提出了一个基于能量的物理模型，该模型可以解释观察到的室温晶界滑动，并在晶体纳米塑性和缺陷微结构演化的框架内讨论了观察结果。
