Strain rate and size effect on dislocation plasticity in single crystalline pillar
作者单位：State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Applied Mechanics Lab. School of Aerospace Engineering Tsinghua University
会议名称：《2018年全国固体力学学术会议》
会议日期：2018年
学科分类：07[理学] 070205[理学-凝聚态物理] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0702[理学-物理学]
关 键 词：Surface nucleation strain rate submicron pillars discrete dislocation dynamic critical size
摘 要：Dislocation plays an important role in the plastic deformation of crystalline materials. The deformation mechanism varies with strain rate, sample size and internal defects. In this work, discrete dislocation dynamics(DDD) are performed to clarify the dislocation controlled plasticity in single crystalline copper pillars with diameter ranging from 100 to 800 nm. It is founded that there is a transition from dislocation multiplication to surface nucleation when strain rate increases or sample size decreases. Two analytical models are established based on the surface nucleation mechanism and the single arm source dominated plasticity, respectively. The critical resolved shear stress at different sizes evaluated by the analytical models matches well with the experiment results. The critical size when the dominated dislocation mechanism transforms is predicted to be ～140 nm.