First-principles investigation on stability and electronic structure of Sc-doped θ′/Al interface in Al−Cu alloys

The properties of Sc-doped θ′ (Al2Cu)/Al interface in Al−Cu alloys were investigated by first-principles calculations. Sc-doped semi-coherent and coherent θ′ (Al2Cu)/Al interfaces (Sc doped in Al slab (S1 site), Sc doped in θ′ slab (S2 site)) were modeled based on calculated results and reported experiments. Through the analysis of interfacial bonding strength, it is revealed that the doping of Sc at S1 site can significantly decrease the interface energy and increase the work of adhesion. In particular, the doped coherent interface with Sc at S1 site which is occupied by interstitial Cu atoms has very good bonding strength. The electronic structure shows the strong Al—Cu bonds at the interfaces with Sc at S1 site, and the Al—Al bonds at the interfaces with Sc at S2 site are formed. The formation of strong Al—Cu and Al—Al bonds plays an important role in the enhancement of doped interface strength.