Universal mechanical response of metallic glasses during strain-rate-dependent uniaxial compression

TL;DR

This study reveals a universal relation governing the mechanical response of metallic glasses under strain-rate-dependent compression, explaining diverse experimental behaviors through temperature effects and internal dissipation variations.

Contribution

The paper introduces a universal relation linking compressive strength and temperature in metallic glasses, unifying diverse strain-rate behaviors through simulations.

Findings

Compressive strength behavior varies with strain rate and alloy type.

Temperature changes mediate the nonmonotonic strength response.

Internal dissipation influences the critical strain rate for behavior transition.

Abstract

Experimental data on the compressive strength $\sigma_{\rm max}$ versus strain rate ${\dot \varepsilon}_{\rm eng}$ for metallic glasses undergoing uniaxial compression shows significantly different behavior for different alloys. For some metallic glasses, $\sigma_{\rm max}$ decreases with increasing ${\dot \varepsilon}_{\rm eng}$, for others, $\sigma_{\rm max}$ increases with increasing ${\dot \varepsilon}_{\rm eng}$, and for others $\sigma_{\rm max}$ versus ${\dot \varepsilon}_{\rm eng}$ is nonmonotonic. Using numerical simulations of metallic glasses undergoing uniaxial compression at nonzero strain rate and temperature, we show that they obey a universal relation for the compressive strength versus temperature, which determines their mechanical response. At low ${\dot \varepsilon}_{\rm eng}$, increasing strain rate leads to increases in temperature and decreases in $\sigma^*_{\rm max}$, whereas at high ${\dot \varepsilon}_{\rm eng}$, increasing strain rate leads to decreases in temperature and increases in $\sigma^*_{\rm max}$. This non-monotonic behavior of $\sigma^*_{\rm max}$ versus temperature causes the nonmonotonic behavior of $\sigma^*_{\rm max}$ versus ${\dot \varepsilon}_{\rm eng}$. Variations in the internal dissipation change the characteristic strain rate at which the nonmonotonic behavior occurs. These results are general for a wide range of metallic glasses with different atomic interactions, damping coefficients, and chemical compositions.