The energy and structure of (1 1 0) twist grain boundary in tungsten

Abstract

The energy and structure of (110) twist grain boundary (TGB) in W are systematically investigated using molecular statics simulations. A dependence of grain boundary energy vs. the twist angle θ 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, (110) TGBs can be divided into three types: low-angle grain boundaries (LAGBs), intermediate-angle grain boundaries (IAGBs) and high-angle grain boundaries (HAGBs). When θ≤16.10°, a regular dislocation network consisting of 12[111], 12[1¯1¯1] and [001] 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°≤θ≤22.22°, both atomistic structures and dislocations are disordered and dislocations do not form a regular network. The TGBs with θ≥23.5° are HAGBs, where no dislocation is observed. The HAGBs can be divided into three sub-types further: special boundaries with low Σ, boundaries in their vicinity with similar structures as the corresponding special boundary in local regions as well as ordinary HAGBs consisting of periodic patterns.