First principles calculations on stability, electronic structure and fracture failure of Cu-doped Al(100)/Mg2Si(111) interface

In order to theoretically clarify the effect of Cu on Al/Mg2Si interface, the calculation method of first principles is employed to determine a stable interface in Al(100)/Mg2Si(111) through surface convergence test and adhesion work. This study aims to investigate the stability, electronic structure, and fracture failure of Cu-doped Al(100)/ Mg2Si(111) interfaces with varying concentrations of Cu. The interfacial bonding strength is the highest when the doping concentration of Cu is 1.85 % according to adhesion work. Comparing with orbital hybridization degree of density of states and pseudogap width of interface total density of states, it can be known that the generation of Mg-Si and Mg-Cu bonds and the best stable Al(100)/Mg2Si(111)-1.85 at.%Cu interface, respectively. The difference charge density shows that the charge density between Al-Cu atoms and Mg-Cu atoms is significantly higher than Al-Si atoms and Mg-Si atoms. The average numbers of transfer per atom at the Al(100)/ Mg2Si(111)-1.85 at.%Cu interface are higher than that at the Cu-undoped Al(100)/Mg2Si(111) interface, indicating an increase in ionic bond strength. Tensile simulations of Al(100)/Mg2Si(111) and Al(100)/Mg2Si(111)- 1.85 at.%Cu interfaces were performed. According to tensile stress-strain curve and difference charge density, cracks are initiated in Mg2Si due to the fracture of Mg-Si and Mg-Cu bonds.