文献类型：期刊文献

英文题名：Stationary dislocation motion at stresses significantly below the Peierls stress: Example of shuffle screw and 60° dislocations in silicon

作者：Chen, Hao[1];Levitas, Valery, I[2,3,4];Xiong, Liming[2];Zhang, Xiancheng[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China;[2]Iowa State Univ, Dept Aerosp Engn, Ames, IA 50011 USA;[3]Iowa State Univ, Dept Mech Engn, Ames, IA 50011 USA;[4]Iowa State Univ, US Dept Energy, Ames Lab, Ames, IA 50011 USA

年份：2021

卷号：206

外文期刊名：ACTA MATERIALIA

收录：;EI(收录号：20210309804832);WOS:【SCI-EXPANDED(收录号:WOS:000620252300036)】；

基金：HC acknowledges supports by Shanghai Sailing Program (20YF1409400) and NSFC of China (52005186). VIL acknowledges supports of NSF (CMMI-1943710 and DMR-1904830), ONR (N00014-19-1-2082), ARO (W911NF-17-1-0225), and Iowa State University (Vance Coffman Faculty Chair Professorship). LX acknowledges the NSF support (CMMI-1930093 and DMR-1807545). VIL and LX acknowledge XSEDE computing resources under MSS170015 and MSS170003. XCZ acknowledges the support from NSFC of China (51725503).

语种：英文

外文关键词：Dynamic Peierls stress; Dislocation mobility; Molecular dynamics; Multiscale modeling

摘要：The stationary motion of shuffle screw and 60 degrees dislocations in silicon when the applied shear, tau(ap), is much below the static Peierls stress, tau(max)(p), is proved and quantified through a series of molecular dynamics (MD) simulations at 1 K and 300 K, and also by solving the continuum-level equation of motion, which uses the atomistic information as inputs. The concept of a dynamic Peierls stress, tau(d)(p), below which a stationary dislocation motion can never be possible, is built upon a firm atomistic foundation. In MD simulations at 1 K, the dynamic Peierls stress is found to be 0.33 GPa for a shuffle screw dislocation and 0.21 GPa for a shuffle 60 degrees dislocation, versus tau(m)(ax)(p) of 1.71 GPa and 1.46 GPa, respectively. The critical initial velocity v(0)(c)(tau(ap)) above which a dislocation can maintain a stationary motion at tau(d)(p) < tau(ap) < tau(m)(ax)(p) is found. The velocity dependence of the dissipation stress associated with the dislocation motion is then characterized and informed into the equation of motion of dislocation at the continuum level. A stationary dislocation motion below tau(m)(ax)(p) is attributed to: (i) the periodic lattice resistance smaller than tau(m)(ax)(p) almost everywhere; and (ii) the change of a dislocation's kinetic energy, which acts in a way equivalent to reducing tau(m)(ax)(p). The results obtained here open up the possibilities of a dynamic intensification of plastic flow and defects accumulations, and consequently, the strain-induced phase transformations. Similar approaches can be applicable to partial dislocations, twin and phase interfaces. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.