Nonequilibrium plastic roughening of metallic glasses yields self-affine topographies with strain-rate and temperature-dependent scaling exponents

TL;DR

This study uses molecular dynamics simulations to analyze how metallic glasses develop self-affine surface roughness during plastic deformation, revealing that roughness characteristics depend on strain-rate and temperature.

Contribution

It demonstrates the strain-rate and temperature dependence of roughness scaling exponents in metallic glasses during plastic flow, providing new insights into nonequilibrium surface roughening.

Findings

Roughness emerges at yield and is reinforced during deformation.

Hurst exponents decrease with increasing strain-rate and temperature.

Roughness amplitude grows with the square root of strain, influenced by rate and temperature.

Abstract

We study nonequilibrium roughening during compressive plastic flow of initially flat Cu$_{50}$Zr$_{50}$ metallic glass using large-scale molecular dynamics simulations. Roughness emerges at atomically flat interfaces beyond the yield point of the glass. A self-affine rough topography is imprinted at yield and is reinforced during subsequent deformation. The imprinted topographies have Hurst exponents that decrease with increasing strain-rate and temperature. After yield, the root-mean-square roughness amplitude grows as the square-root of the applied strain with a prefactor that also drops with increasing strain-rate and temperature. Our calculations reveal the emergence of spatial power-law correlations from homogeneous samples during plastic flow with exponents that depend on the rate of deformation and the temperature. The results have implications for interpreting and engineering roughness profiles.