Effects of Elements on Mechanical and Electronic Properties of Ag from First-Principles Calculations

Abstract

The first-principles calculations were performed to research effects of elements X (Au, Be, Pd, Y, Ca, Cu, In and Zn) on mechanical and electronic properties of Ag with the density function theory (DFT). A supercell consisting of 107 atoms of Ag and one solute atom X was used. It was found that the bulk modulus of Ag dilute solutions were affected by the bulk modulus of pure alloying elements as well as their volume. The shear modulus G trend to decrease with increase of volume of Ag caused by alloying addition, but Ag-X covalent bond had positive correlation with shear modulus G. All of Ag107X alloys were ductility since theirs B/G ratio, Poisson's ratios ν were larger than 1.75 and 0.33, respectively. Comparing to other calculated Ag107X alloys, Ag107Be and Ag107Cu had the larger Vickers hardness, the value of which were 3.96GPa, 3.86GPa, respectively. There were not only metallic bonds (Ag-Ag) but also covalent bonds (Ag-X) in Ag107X alloys. The strong covalent bonds between Y, Zn, Ca and Ag were mainly caused by orbital hybridization between Y-5p orbital, Zn-3d orbital, Ca-3d orbitals and Ag-4d, 5s and 5p orbitals.