The energy and structure of (110) twist grain boundary in tungsten

The energy and structure of (1 1 0) twist grain boundary (TGB) in W are systematically investigated using molecular statics simulations. A dependence of grain boundary energy vs. the twist angle theta over the entire angular range is obtained and agrees well with the modified Read-Shockley equation in low-angle range. According to the analysis of dislocations in grain boundaries, (1 1 0) TGBs can be divided into three types: low-angle grain boundaries (LAGBs), intermediate-angle grain boundaries (IAGBs) and high-angle grain boundaries (HAGBs). When theta <= 16.10 degrees, a regular dislocation network consisting of 1/2[1 1 1], 1/2[(1) over bar(1) over bar1] and[0 0 1] screw dislocations exists in LAGBs. And the size and shape of meshes in the network vary with increased twist angles. In IAGBs, with 17.23 degrees <= theta <= 22.22 degrees, both atomistic structures and dislocations are disordered and dislocations do not form a regular network. The TGBs with theta >= 23.5 degrees are HAGBs, where no dislocation is observed. The HAGBs can be divided into three sub-types further: special boundaries with low Sigma, boundaries in their vicinity with similar structures as the corresponding special boundary in local regions as well as ordinary HAGBs consisting of periodic patterns. (C) 2015 Elsevier B.V. All rights reserved.