Variability of non-Schmid effects in grain boundary dislocation nucleation criteria

详细信息    查看全文

• 作者：Ricky D. Wyman^a ; David T. Fullwood^a ; Robert H. Wagoner^b ; Eric R. Homer^a ; ^{eric.homer@byu.edu}
• 关键词：Grain boundaries ; Dislocation nucleation ; Molecular dynamics
• 刊名：Acta Materialia
• 出版年：2017
• 出版时间：1 February 2017
• 年：2017
• 卷：124
• 期：Complete
• 页码：588-597
• 全文大小：4199 K
• 卷排序：124

文摘

Grain boundary dislocation nucleation is simulated in a Nickel bicrystal with Σ21b (211)/(211) grain boundaries. Using molecular dynamics, 386 different triaxial stress states are examined for their effect on dislocation nucleation on different slip systems. The approach leads to dislocation nucleation on six of the twelve partial slip systems, enabling a study of conditions leading to nucleation. The criteria for nucleation on each of the slip systems is shown to have a linear dependence on the resolved shear, normal, and co-slip stresses, though the constants for this linear dependence are unique for each slip system. The combined nucleation criteria are used to construct a theoretical nucleation surface. The surface is reminiscent of a Mohr-Coulomb yield surface, except that in the present case the facets of the surface correspond to nucleation on different slip systems.