Structures and energies of Σ 3 asymmetric tilt grain boundaries in copper and aluminium

Abstract

The objective of this research is to use atomistic simulations to investigate the energy and structure of symmetric and asymmetric Σ3 ⟨110⟩ tilt grain boundaries. A nonlinear conjugate gradient algorithm was employed along with an embedded atom method potential for Cu and Al to generate the equilibrium 0 K grain boundary structures. A total of 25 ⟨110⟩ grain boundary structures were explored to identify the various equilibrium and metastable structures. Simulation results show that the Σ3 asymmetric tilt grain boundaries in the ⟨110⟩ system are composed of only structural units of the two Σ3 symmetric tilt grain boundaries. The energies for the Σ3 grain boundaries are similar to previous experimental and calculated grain boundary energies. A structural unit and faceting model for Σ3 asymmetric tilt grain boundaries fits all of the calculated asymmetric grain boundary structures. The significance of these results is that the structural unit and facet description of all Σ3 asymmetric tilt grain boundaries may be predicted from the structural units of the Σ3 coherent twin and incoherent twin boundaries for both Cu and Al.

Acknowledgement

This material is based on work supported under a National Science Foundation Graduate Research Fellowship (M.A.T.). We acknowledge the support of the IHPCL at Georgia Tech. and the NCSA at UIUC for use of their computational resources. D.L. McDowell is grateful for the additional support of this work by the Carter N. Paden, Jr. Distinguished Chair in Metals Processing.