Method for Computing Short-Range Forces between Solid-Liquid Interfaces Driving Grain Boundary Premelting

TL;DR

This paper introduces a molecular dynamics method to accurately compute short-range forces at solid-liquid interfaces, revealing their dominance in grain boundary premelting near the melting point.

Contribution

The paper presents a novel molecular dynamics approach to quantify short-range structural forces at grain boundaries close to melting, improving understanding of premelting mechanisms.

Findings

Short-range repulsion dominates over long-range forces near melting point.

Nanometer-scale premelting layers are observed only very close to melting.

Method accurately captures interface fluctuations and free-energy profiles.

Abstract

We present a molecular dynamics based method for computing accurately short-range structural forces resulting from the overlap of spatially diffuse solid-liquid interfaces at wetted grain boundaries close to the melting point. The method is based on monitoring the fluctuations of the liquid layer width at different temperatures to extract the excess interfacial free-energy as a function of this width. The method is illustrated for a high energy Sigma 9 twist boundary in pure Ni. The short-range repulsion driving premelting is found to be dominant in comparison to long-range dispersion and entropic forces and consistent with previous experimental findings that nanometer-scale layer widths may only be observed very close to the melting point.