Cooling under applied stress rejuvenates amorphous alloys and enhances their ductility

TL;DR

Applying tensile stress during cooling rejuvenates amorphous alloys, increasing their potential energy and ductility, which could lead to improved manufacturing processes for more plastic metallic glasses.

Contribution

This study demonstrates how tensile stress during cooling affects the structure and mechanical properties of binary glasses, revealing a method to enhance ductility.

Findings

Higher applied stress increases potential energy and contacts between atoms.

Rejuvenated glasses show reduced elastic modulus and stress overshoot.

Enhanced ductility observed in glasses cooled under higher tensile stress.

Abstract

The effect of tensile stress applied during cooling of binary glasses on the potential energy states and mechanical properties is investigated using molecular dynamics simulations. We study the three-dimensional binary mixture that was first annealed near the glass transition temperature and then rapidly cooled under tension into the glass phase. It is found that at larger values of the applied stress, the liquid glass former freezes under higher strain and its potential energy is enhanced. For a fixed cooling rate, the maximum tensile stress that can be applied during cooling is reduced upon increasing initial temperature above the glass transition point. We also show that the amorphous structure of rejuvenated glasses is characterized by an increase in the number of contacts between smaller type atoms. Furthermore, the results of tensile tests demonstrate that the elastic modulus and the peak value of the stress overshoot are reduced in glasses prepared at larger applied stresses and higher initial temperatures, thus indicating enhanced ductility. These findings might be useful for the development of processing and fabrication methods to improve plasticity of bulk metallic glasses.