Glass-forming ability and atomic-level structure of the ternary Ag–Ni–Zr metallic glasses studied by molecular dynamics simulations

Abstract

Based on the recently proposed long-range empirical potential formulism, an n-body potential is constructed for the Ag–Ni–Zr ternary metal system and verified to be realistic by reproducing some important properties of the pure metals as well as of some equilibrium compounds of the system. Applied the constructed Ag–Ni–Zr potential, molecular dynamics simulations and Voronoi tessellations are then carried out to study the effect of alloying composition on glass-forming ability and atomic-level structure of the ternary Ag–Ni–Zr metallic glasses. For the Ag50−x/2 NixZr50−x/2 alloys, with increasing Ni concentration, distortion of the crystalline structure becomes significant, implying a disordering process going on, and at the same time, the number of {0, 0, 12, 0} icosahedrons increases remarkably and the {0, 0, 12, 0} icosahedrons are almost Ni-centered. When the Ni concentration is increased up to 20 atom %, the ternary Ag–Ni–Zr solid solution collapses and turns into a disordered state, suggesting that increasing the Ni concentration could enhance the glass-forming ability of the system. For the Ag30Ni40Zr30 ternary metallic glass, it is found that most of the polyhedrons with coordinate number (CN < 13) are Ni-centered, whereas most of polyhedrons with CN > 14 are either Ag or Zr centered.