Zhu Ting, Li Ju, Yip Sidney
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2004 Jul 9;93(2):025503. doi: 10.1103/PhysRevLett.93.025503.
We report the first atomistic calculation of the saddle-point configuration and activation energy for the nucleation of a 3D dislocation loop from a stressed crack tip in single crystal Cu. The transition state is found using reaction pathway sampling schemes, the nudged elastic band, and dimer methods. For the (111)[110] crack, loaded typically at 75% of the athermal critical strain energy release rate for spontaneous dislocation nucleation, the calculated activation energy is 1.1 eV, significantly higher than the continuum estimate. Implications concerning homogeneous dislocation nucleation in the presence of a crack-tip stress field are discussed.
我们报告了对单晶铜中应力裂纹尖端三维位错环形核的鞍点构型和活化能的首次原子尺度计算。使用反应路径采样方法、推挤弹性带法和二聚体方法找到了过渡态。对于(111)[110]裂纹，通常在自发位错形核的无热临界应变能释放率的75%下加载，计算得到的活化能为1.1电子伏特，显著高于连续介质估计值。讨论了在裂纹尖端应力场存在下均匀位错形核的相关影响。
