Schiøtz Jakob, Jacobsen Karsten W
Center for Atomic-Scale Materials Physics (CAMP), Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark.
Science. 2003 Sep 5;301(5638):1357-9. doi: 10.1126/science.1086636.
We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15 nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence of the strength of polycrystalline metals.
我们使用了系统规模达1亿个原子的分子动力学模拟来模拟纳米晶铜的塑性变形。通过将晶粒尺寸在5至50纳米之间变化，我们发现流动应力以及强度在晶粒尺寸为10至15纳米时呈现最大值。这一最大值是由于微观变形机制从粗晶材料中的位错介导塑性转变为纳米晶区域中的晶界滑动。这些模拟使我们能够观察到多晶金属强度与晶粒尺寸相关性背后的机制。
