钛单晶纳米柱拉压不对称性的分子动力学模拟

Study on the Unsymmetry of Tension and Compression in Titanium Single-crystal Nanopillars Based on Molecular Dynamics Simulation

摘要:

本文基于分子动力学模拟,通过研究钛单晶纳米柱在拉伸和压缩下的力学响应特征及晶体结构演化行为,揭示其塑性变形机制。结果表明沿[0001]晶向拉伸条件下主要塑性变形机制为伴生的{101 ?2}孪晶和基面层错；而沿[0001]晶向压缩条件下,基面位错作为优先形核的缺陷参与到塑性变形过程,随后锥面位错出现并协调了轴向和横向变形,压缩条件下无孪晶产生。拉伸模拟过程中观察到一种有别于传统孪生的晶体再取向现象,其孪晶与基体间呈现基面/柱面对应关系。

Abstract:

The plastic deformation mechanisms of the titanium single-crystal nanopillars under both tension and compression were studied with the molecular dynamics simulation method. In this work, the research focuses on two aspects around the microscopic deformation mechanisms: stress-strain analysis and the evolution of atomistic configuration. The results indicate that the {101 ?2} twinning and stacking fault dominate the tension deformation along the [0001] direction. The slip is the principal factor leading to the initial yielding and then the pyramidal slip occurs to coordinate both vertical and horizontal strains for the compression condition along the [0001] direction. Additionally, no twinning is found in compression. Besides the conventional {101 ?2} plane, semi-coherent basal-prismatic interfaces between parent and reoriented crystal were also observed under tensile loading.