First principles study on the influence of multi-element doping on the mechanical properties of /Al interface in Al-Cu alloy

The influence of substitution doping of Ca, Co and Si atoms on the tensile and shear deformation mechanisms of Al/Al2Cu interfaces are investigated by first-principles calculations. Al2 terminated interface is the most stable interface structure in Al-Al2Cu configuration. Compared with the stress-strain curves of pristine phase, doping atoms can enhance the elongation of interface structure due to the electron enrichment around doping atoms and Al atoms. Moreover, Co atom also promotes the yield strength of interface, and its fracture toughness is the largest among all interfaces, which illustrates Co-doped interface has the largest ductility. Generalized-stacking-fault energy (GSFE) is calculated for estimation of shear resistance. The relationship between the maximum slope of GSFE and the yield strength is also discussed. Results show that slip is more difficult to occur at Ca-doped interface than other interfaces. The reasons can be summarized as follows: the improvement of GSFE local maxima is related to the electron enrichment around doping atom, while the increase of local minima can be attributed to the electron enrichment between other atoms.