On the deformation and failure mechanisms of hydrogen alloyed metallic glasses

While microalloying of metallic glasses (MGs) using hydrogen emerged a few years ago, the underlying mechanism of how hydrogen microalloying influences mechanical behaviors is currently still under debate. Herein, we perform atomistic simulations to investigate the effect of hydrogen microalloying on the mechanical profiles of MGs. The mitigation of strain localization accompanied with plenty of shear transformation zones (STZs) is exhibited in H-alloyed MGs and becomes more significant with the increase of H content. The addition of hydrogen induces a loose atomic structure with fertile liquid-like regions and abundant free volume, which triggers more STZ events and the softening behavior. Furthermore, hydrogen doping lowers the STZ activation energy barrier, which is verified by a theoretical model based on the concept of energetic criterion. Our work provides some new insight on how to tune the local packing of MGs and further alter the deformation behavior.