Effect of hydrogen charging on pop-in behavior of a zr-based metallic glass

In this work, structural and mechanical properties of hydrogen-charged metallic glass are studied to evaluate the effect of hydrogen on early plasticity. Hydrogen is introduced into samples of a Zr-based (Vit 105) metallic glass using electrochemical charging. Nanoindentation tests reveal a clear increase in modulus and hardness as well as in the load of the first pop-in with increasing hydrogen content. At the same time, the probability of a pop-in occurring decreases, indicating that hydrogen hinders the onset of plastic instabilities while allowing local homogeneous deformation. The hydrogen-induced stiffening and hardening is rationalized by hydrogen stabilization of shear transformation zones (STZs) in the amorphous structure, while the improved ductility is attributed to the change in the spatial correlation of the STZs.