Symmetric and asymmetric tilt grain boundary structure and energy in Cu and Al (and transferability to other fcc metals)

Abstract

Symmetric and asymmetric tilt grain boundaries in Cu and Al were generated using molecular statics energy minimization in a classical molecular dynamics code with in-plane grain boundary translations and an atom deletion criterion. The following dataset (NIST repository, http://hdl.handle.net/11256/358) contains atomic coordinates for minimum energy grain boundaries in three-dimensional periodic simulation cells, facilitating their use in future simulations. This grain boundary dataset is used to show the relative transferability of grain boundary structures from one face-centered cubic system to another; in general, there is good agreement in terms of grain boundary energies (R 2 > 0.99). Some potential applications and uses of this tilt grain boundary dataset in nanomechanics and materials science are discussed.

Emergence of directionally-anisotropic mobility in a faceted Ʃ11 ⟨110⟩ tilt grain boundary in Cu

“…It . Ʃ5 tilt boundaries have a predictable structure while also having energies similar to those of general high-angle interfaces [5,36], which can be found in Table 1. (Table 1) and the interconnectivity of free volume between E units [20].…”

“…An asymmetric Ʃ5 <001> tilt boundary (β = 32.5°) was also generated and probed to provide a boundary that is asymmetric without faceting for comparison. Fully periodic simulation cells were generated in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [26], using code developed by Tschopp et al [5] for the identification of minimum energy grain boundary structures. This algorithm uses a series of iterating shifts and atom deletions to probe all possible periodic structures for the given crystal orientations and also calculates grain boundary energy.…”

“…The understanding of boundary faceting can be broadened by looking beyond Ʃ3 grain boundaries to investigate other low-index coincident site lattice (CSL) interfaces, with the Ʃ11 <110> tilt grain boundary in particular standing out as a potentially interesting system. The static structures of various symmetric and asymmetric Ʃ11 boundaries have been studied in prior work [2,3,5,[18][19][20][21][22], providing a rich knowledge base showing that faceting is common. For example, Brown and Mishin [3] showed that the high energy segments of faceted Ʃ11 boundaries are often oriented along an unusual plane, the {001}/{111} interface, which is not a member of the Ʃ11 CSL boundary set.…”

Grain boundary properties of elemental metals

“…Computationally, there have been many investigations of γ GB using both empirical and first principles methods. Studies using empirical interatomic potentials (IAPs) such as the embedded atom method (EAM) [31,32,33] and Lennard-Jones [31,32] potentials are typically limited to a few elemental systems belonging to a specific crystal prototype (e.g., fcc or bcc), but cover a broad range of GB types [34,35,36,37,38,39]. The reason is because the fitting of sufficiently accurate IAPs is a relatively complex and resourceintensive process, but once fitted, it is inexpensive to use the IAP to compute many GB structures comprising thousands or even millions of atoms.…”

Silicon particle pinhole defects in aluminium–silicon alloys

“…1a2. Their presence is easily liquid aluminium at the eutectic temperature [34][35][36]) and aluminium grain boundary energies roughly between 0.2 and 0.6 J/m 2 [37,38], given the long hold times and high temperatures of heat-treatment, the formation of broad ridges characteristic of equilibration with a finite dihedral angle in the middle of the range between 0 and 180°makes sense. Along the linear burr-like ridges no intermetallic particles were observed; this was also the case for the grooves and the steps.…”