Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
J Phys Chem A. 2013 Jun 27;117(25):5326-34. doi: 10.1021/jp401368t. Epub 2013 Jun 18.
Dislocation mediated plasticity in the α phase of the energetic molecular crystal cyclotrimethylene trinitramine (RDX) was investigated using a combination of atomistic simulations and the Peierls-Nabarro (PN) model. A detailed investigation of core structures and dislocation Peierls stress was conducted using athermal atomistic simulations at atmospheric pressure to determine the active slip systems. Generalized stacking fault energy surfaces calculated using atomistic simulations were used in the PN model to also estimate the critical shear stress for dislocation motion. The primary slip plane is found to be (010) in agreement with experimental observations, with the (010)[100] slip systems having the lowest Peierls stress. In addition, atomistic simulations predict the (021)[01[overline]2], (021)[100], (011)[100], (001)[100], and (001)[010] slip systems to have Peierls stress values small enough to allow plastic activity. However, there are less than five independent slip systems in this material in all situations. The ranking of slip systems based on the Peierls stress values is provided, and implications are discussed in relation to experimental data from nanoindentation and shock-induced plastic deformation.
利用原子模拟和派尔斯-纳巴罗（Peierls-Nabarro，PN）模型相结合的方法，研究了高能分子晶体环三亚甲基三硝胺（RDX）的α相位错介导的塑性。通过在常压下进行非平衡态原子模拟，对核心结构和位错派尔斯应力进行了详细的研究，以确定活性滑移系统。利用原子模拟计算得到的广义层错能面被用于 PN 模型，以估计位错运动的临界剪切应力。发现主要的滑移面与实验观察结果一致，为（010），且（010）[100]滑移系统具有最低的派尔斯应力。此外，原子模拟预测（021）[01[overline]2]、（021）[100]、（011）[100]、（001）[100]和（001）[010]滑移系统的派尔斯应力值足够小，可以允许塑性活动。然而，在所有情况下，这种材料的独立滑移系统都少于五个。提供了基于派尔斯应力值的滑移系统的排序，并讨论了与纳米压痕和冲击诱导塑性变形的实验数据相关的影响。
