Second-Nearest-Neighbor Correlations from Connection of Atomic Packing Motifs in Metallic Glasses and Liquids

TL;DR

This study uses molecular dynamics simulations to analyze atomic correlations in metallic glasses and liquids, revealing how cluster connections influence the structure and elastic properties during the transition from liquid to glass.

Contribution

It introduces a connection scheme based on shared atoms between atomic packing motifs to explain the second RDF peak in metallic glasses and liquids.

Findings

Face-sharing cluster connections are most favored in the glass transition.

Splitting of the second RDF peak originates from cluster connections in the liquid.

Cluster connection properties are consistent across different alloys.

Abstract

Using molecular dynamics simulations, we have studied the atomic correlations characterizing the second peak in the radial distribution function (RDF) of metallic glasses and liquids. The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared atoms between two linked coordination polyhedra. The results demonstrate that the cluster connections by face-sharing, specifically with three common atoms, are most favored when transitioning from the liquid to glassy state, and exhibit the stiffest elastic response during shear deformation. These properties of the connections and the resultant atomic correlations are generally the same for different types of packing motifs in different alloys. Splitting of the second RDF peak was observed for the inherent structure of the equilibrium liquid, originating solely from cluster connections; this trait can then be inherited in the metallic glass formed via subsequent quenching of the parent liquid through the glass transition, in the absence of any additional type of local structural order. Increasing ordering and cluster connection during cooling, however, may tune the position and intensity of the split peaks.