Effect of alloying elements (Ti, Zn, Zr, Al) on the interfacial properties of Cu/Ni2Si: A DFT study

The addition of trace alloying elements to metal matrix composites has an important effect on their interfacial bonding properties and strength. In this study, the electronic structure, interfacial stability, and bonding properties of Cu/Ni₂Si interfaces with doping alloying elements are systematically investigated on the atomic scale. It was found that the addition of alloying elements to the Cu side of the Cu(100)/Ni₂Si(101)-Ni interface improved the interfacial stability, where Ti, Zn, Zr, and Al increased the interfacial work of adhesion from 2.53 J/m² to 3.04 J/m², 2.65 J/m², 3.20 J/m², and 2.82 J/m², respectively. When alloying elements were doped in the sub-interfacial and third interfacial layers, only Zr enhances interfacial stability significantly. Analyses of interfacial and electronic structures show that Ti and Zr stabilize the Cu(100)/Ni₂Si(101) interface through strong chemical bonds, while Zn and Al reduce interface distortion energy. The thermodynamic stability of the interface increases with higher doping rates. Moreover, increased adhesion tends to enhance the wettability of heterogeneous interfaces. At a 16.6% doping rate of the interfacial layer, Ti and Zr have the most significant effect on the contact angle, reducing it from 98.8° to 89.1° and 86.2°, respectively, thus promoting the wetting process.