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

摘要

The objective of this research is to use atomistic simulations to investigate the energy and structure of symmetric and asymmetric Sigma 3 < 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 Sigma 3 asymmetric tilt grain boundaries in the < 110 > system are composed of only structural units of the two Sigma 3 symmetric tilt grain boundaries. The energies for the Sigma 3 grain boundaries are similar to previous experimental and calculated grain boundary energies. A structural unit and faceting model for Sigma 3 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 Sigma 3 asymmetric tilt grain boundaries may be predicted from the structural units of the Sigma 3 coherent twin and incoherent twin boundaries for both Cu and Al.