Atomistic simulations were used to investigate the structure and energy of asymmetrical tilt grain boundaries in Cu and Al. Among those examined were the Σ5 and Σ13 systems, with a boundary plane rotated about the <100> misorientation axis, and the Σ9 and Σ11 systems, rotated about the <110> misorientation axis. Asymmetrical tilt grain boundary energies were calculated as a function of the inclination angle and were compared with an energy relationship that was based upon faceting into the 2 symmetrical tilt grain boundaries in each system. It was found that asymmetrical tilt boundaries with low-index normals did not necessarily have lower energies than boundaries with similar inclination angles; contrary to previous conclusions. Further analysis of grain-boundary structures provided some insight into the asymmetrical tilt grain boundary energy. The Σ5 and Σ13 systems in the <100> system agreed with the aforementioned energy relationship. The structures confirmed that these asymmetrical boundaries faceted into the symmetrical tilt boundaries. The Σ9 and Σ11 systems in the <110> system deviated from the idealized energy relationship. As the boundary inclination angle increased towards the Σ9 (221) and Σ11 (332) symmetrical tilt boundaries, the minimum-energy asymmetrical boundary structures contained low-index {111} and {110} planes bounding the interface region.

Asymmetric Tilt Grain Boundary Structure and Energy in Copper and Aluminium. M.A.Tschopp, D.L.Mcdowell: Philosophical Magazine, 2007, 87[25], 3871-92