Plasticity trends in Ag-based disordered solid solutions from first principles

Ag-based solid solutions have attracted attention owing to their excellent plasticity to reduce the requirements of temperature, pressure, and surface flatness for solid-state bonding in electronic packaging field. In this study, the elastic constants and modulus, stacking fault energies (SFEs), twinnability, ideal shear strength and critical twinning stress of Ag-based solid solutions were computed using first-principles calculations. All the solid solutions studied were disordered, with Pt, Au, Zn, Ga, and Sn as solute elements. An approximate proportional correlation between unstable stacking fault energy and the product of shear modulus and Burger vector was identified. Notably, the average chemical and modulus mismatch factors were introduced to predict the changes in plasticity as a function of the alloying elements. These predictions were supported by results of ideal shear strength and critical twinning stress. Compared to others, the higher plasticity exhibited by (Ag)–8.33Sn positioned it as a promising material for the solid-state bonding application. The plasticity trends of various Ag-based disordered solid solutions were summarized, providing a theoretical basis for the selection of solid-state bonding materials in electronic packaging.