Characterizing twist grain boundaries in BCC Nb by molecular simulation: Structure and shear deformation

• Published in: Applied surface science 2016-05, Vol.370, p.19-24
• Main Authors: Liu, Zeng-Hui, Feng, Ya-Xin, Shang, Jia-Xiang
• Format: Article
• Language: English
• Subjects: Atomic structure; Boundaries; Dislocations; Grain boundaries; Lattice sites; Molecular dynamics; Molecular structure; Niobium; Shear; Shear responses; Twist grain boundary
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.02.097

[Display omitted] •A dependence of twist grain boundary energy in BCC Nb over the entire angular range is obtained.•Pure sliding behavior is found at all TWGBs and a dependence of grain boundary shear response vs the twist angle is obtained. Atomic scale modeling was used to study the structure, energy and shear behaviors of (110) twist grain boundaries (TWGBs) in body-centered cubic Nb. The relation between grain boundary energy (GBE) and the twist angle θ agrees well with the Read-Shockley equation in low-angle range. At higher angles, the GBEs show no distinct trend with the variation of the twist angle or the density of coincident lattice sites. All (110) twist boundaries can be classified into two types: low-angle grain boundaries (LAGBs) and high-angle grain boundaries (HAGBs). LAGBs contain a hexagonal dislocation network (HDN) which is composed of 12[111], 12[1¯1¯1] and [001] screw dislocations. HAGBs can be classified into three sub-types further: special boundaries with low Σ, boundaries in the vicinity of special boundaries with similar structures and ordinary HAGBs consisting of periodic patterns. Besides, a dependence of grain boundary shear response vs the twist angle over the entire twist angle range is obtained. Pure sliding behavior is found at all TWGBs. When θ