Interfacial stability of θ′/Al in Al-Cu alloys

Designing low-energy interface structures is crucial in growth and coarsening studies of Al2Cu (theta') precipitates. Given new experimental insights into the theta'/Al system, we use Density Functional Theory (DFT) calculations to investigate the energetics of the coherent (001)(theta')//(001)(Al) and semi-coherent (010)(theta')//(010)(Al) interfaces. We find that the recently proposed occupancy of interstitial Cu atoms at the coherent interface by Bourgeois et al. increases interfacial energy, and hence, is likely due to kinetic effects. For the semi-coherent interface, the semi coherent interfacial energy does not significantly depend on interfacial configurations or misfit strains up to 10-unit cells of Al. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.