Cooperative atomic motion during shear deformation in metallic glass

Abstract

Elucidating mechanical deformation in glassy materials at the atomic level is challenging due to their disordered atomic structure. Using our novel "frozen atom analysis," we reveal that anelastic deformation in CuZr metallic glasses is fundamentally driven by cooperative atomic motions of approximately 40 elastically linked atoms, forming trigger groups. They initiate localized rearrangements, which can cascade into plastic flow. Notably, these groups show no distinct structural or physical features, challenging the idea that deformation occurs in defective regions. Instead, deformation events are highly stochastic and transient, driven by collective atomic motion. This finding not only reshapes our understanding of glassy material deformation mechanisms but also highlights cooperative motion as a key factor in avalanche-like phenomena governing the behavior of disordered systems across multiple scales.