Rejuvenation engineering in metallic glasses by complementary stress and structure modulation

TL;DR

This paper explores how complementary stress and structure modulation can be used to engineer metallic glasses, enhancing their ductility and strain hardening by understanding elastic heterogeneities and shear band activity through experimental and simulation methods.

Contribution

It introduces a combined approach of stress and structure modulation for metallic glasses, supported by experimental and atomistic simulation evidence.

Findings

Large elastic fluctuations observed after deformation

Competing hardening-softening mechanisms identified

Shear band formation correlates with elastic heterogeneities

Abstract

Residual stress engineering is very widely used in the design of new advanced lightweight materials. For metallic glasses the attention has been on structural changes and rejuvenation processes. High energy scanning X-ray diffraction strain mapping reveals large elastic fluctuations in metallic glasses after deformation under triaxial compression. Microindentation hardness mapping hints to a competing hardening-softening mechanism after compression and further reveals the complementary effects of stress and structure modulation. Transmission electron microscopy proves that structure modulation under room temperature deformation relates to the shear band formation that closely correlates to the distribution of elastic heterogeneities. Molecular dynamics simulations provide an atomistic understanding of the complex shear band activity in notched metallic glasses and the related fluctuations in the strain/stress heterogeneity. Thus, future focus should be given to stress engineering and elastic heterogeneity that together with structure modulation may allow to design metallic glasses with enhanced ductility and strain hardening ability.