Revealing structural evolution during stress relaxation in metallic glass by nanoindentation and molecular dynamic simulation

Abstract

Capturing structural evolution information during stress relaxation is crucial to advancing the understanding of deformation mechanisms in metallic glass (MG). However, at room temperature, stress relaxation in most metallic glasses (MGs) is minimal, limiting progress in addressing these scientific challenges. This study investigates the room-temperature stress relaxation of Cu₅₀Zr₅₀ MG using nanoindentation and molecular dynamics (MD) simulations to elucidate atomic rearrangements and deformation mechanisms. Nanoindentation experiments revealed that loads reduce in a time-dependent manner, and both modulus and hardness diminish after relaxation. The Kohlrausch-Williams-Watts (KWW) function was utilized to simulate the stress relaxation behaviors. It was found that as the indentation depth increases, the dynamic heterogeneity increases. Complementary MD simulations illustrated atomic rearrangements during relaxation, visualized through nonaffine displacement distributions.