Influence of atom termination and stacking sequence on the θ′/Al interfaces from first-principles calculations

First-principles calculations was used to explore the influence of atom termination and stacking sequence on the interface strength and stability between theta '(Al2Cu) precipitate and Al matrix along experimentally observed orientations, (001)theta '/(001)Al and (010)theta '/(010)Al interfaces. Six interfacial structures were modeled, and work of adhesion, bonding characters, number of valence electrons and thermal stability had been studied. Calculated results revealed that the Cu-terminated interface has larger work of adhesion than Al terminated interface, and hollow site stacking sequence, with stronger bonding, is superior to top site stacking sequence, adhesion strength for coherent (001)theta '/(001)Al interface is better than that for semi-coherent (010)theta '/(010)Al interface. These differences are attributed to the bonding feature and number of valence electrons. Among the six interface models, the Cu-terminated (001)theta '/(001)Al interface with hollow site stacking has the largest work of adhesion and the smallest interface energy, indicating that it has the best mechanical and thermodynamic properties. (C) 2016 Elsevier Ltd. All rights reserved.