ATOMISTIC SIMULATIONS OF GRAIN BOUNDARY DISLOCATION NUCLEATION

摘要：

Atomistic simulations are used to investigate dislocation nucleation from symmetric and asymmetric tilt grain boundaries in fcc Cu and Al.The use of a 3D periodic bicrystal configuration enables the investigation of how the boundary degrees of freedom impact both boundary structure and dislocation nucleation from these boundaries.Simulation results show that dislocation nucleation from asymmetric tilt grain boundaries requires understanding of the structure and faceting of these boundaries.Deformation simulations under uniaxial tension and compression show entirely different nucleation mechanisms,i.e.,nucleation of full dislocations in copper from the grain boundary under compression.The resolved stress normal to the slip plane on which the dislocation nucleates plays an important role in dislocation nucleation for single crystals and interfaces.We further investigate dislocation nucleation from certain twin boundaries,e.g.,∑171 vicinal coherent twin boundary in Cu.Simulation results show that the symmetric tilt boundary structure is composed of alternating 1/3<111>disconnections with a dissociated structure in copper.Deformation simulations of a 3D periodic bicrystal configuration under uniaxial tension and compression show very different nucleation mechanisms.Results for various symmetric and asymmetric grain and twin boundaries are summarized.

关键词： grain boundaries dislocation nucleation atomistics MD

作者: Mark Tschopp David L.McDowell

作者单位: UTC,Air Force Researck Laboratory,WPAFB,Dayton,OH.USA School of Materials Science & Engineering,Woodruff School of Mechanical Engineering,Georgia Institut

会议类型: 国际会议

会议名称: 第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)

会议地点: 安徽黄山

会议语种:英文

页码: 97-104

在线出版日期: 2008-06-03（万方平台首次上网日期，不代表论文的发表时间）