Insight into the strengthening and fracture mechanism of Au/Ni3Al interface via first-principles calculations

The effects of alloy elemental segregation on the Au/Ni₃Al interface are systematically investigated employing density functional theory (DFT)-based first-principles calculations. Through comprehensive atomic-scale and electronic structure analyses, the mechanisms of interfacial strengthening, elemental segregation behavior, and fracture initiation are elucidated. The findings indicate that the bridge position (MT) configuration has the maximum bond strength. Si and Ge atoms are easily separated from the Au surface to the interface, while Ni and Sn solute atoms exhibit preferential segregation within the Au matrix. When the Ni is doped, the interfacial work of adhesion increased by 16.33 % compared with the undoped interface, and the bonding strength was considerably improved. Meanwhile, the changes of chemical bonding and electronic behavior during the interfacial fracture are systematically analyzed. The fracture of three interfacial stacking models occurred inside the Au bulk phase, which are caused by the breakage of Au-Au(I) bonds in the Au bulk material. This study is a guide to the strengthening, segregation of alloying elements and fracture behavior between Au-based solder materials and base materials.