Center for Materials Processing and Tribology, Purdue University, West Lafayette, Indiana 47907-2023, USA.
Phys Rev Lett. 2012 Sep 7;109(10):106001. doi: 10.1103/PhysRevLett.109.106001. Epub 2012 Sep 4.
Using in situ imaging, we report surface fold formation and fluidlike flow instabilities in sliding of annealed copper. We demonstrate using simulations that folding is principally driven by grain-induced plastic instability. The phenomenon shows remarkable similarities with Kelvin-Helmholtz-type flow instabilities in fluids. While such instabilities have been conjectured to exist in sliding interfaces at the nanoscale, we find vortices and folding in metals at the mesoscale. The occurrence of folds impacts many applications, including surface generation processes and tribology.
利用原位成像，我们报告了退火铜滑动过程中的表面褶皱形成和类似流体的流动不稳定性。我们通过模拟证明，褶皱主要是由晶粒诱导的塑性失稳驱动的。这一现象与流体中的开尔文-亥姆霍兹型流动不稳定性具有显著的相似性。虽然人们推测在纳米尺度的滑动界面中存在这种不稳定性，但我们在金属的介观尺度上发现了涡旋和褶皱。褶皱的出现影响着许多应用，包括表面生成过程和摩擦学。
