Strain effects at solid surfaces near the melting point

TL;DR

This paper explores how strain influences surface melting near the melting point, revealing strain-induced effects on film thickness and phase transitions, supported by molecular dynamics simulations of strained aluminum surfaces.

Contribution

It introduces the concept that strain can modulate surface melting behavior and induce prewetting transitions, a novel insight into surface phase phenomena near melting.

Findings

Strain lowers the bulk melting point.

Strain affects surface free energy and melting behavior.

Molecular dynamics simulations confirm theoretical predictions.

Abstract

We investigate the effects of strain on a crystal surface close to the bulk melting temperature T_m, where surface melting usually sets in. Strain lowers the bulk melting point, so that at a fixed temperature below but close to T_m the thickness of the quasi-liquid film is expected to grow with strain, irrespective of sign. In addition, a strain-induced solid surface free energy increase/decrease takes place, favoring/disfavoring surface melting depending on the sign of strain relative to surface stress. In the latter case one can produce a strain-induced prewetting transition, where for increasing temperature the liquid film suddenly jumps from zero to a finite thickness. This phenomenology is illustrated by a realistic molecular dynamics simulation of strained Al(110).