Effect of hydrogen on subsurface deformation during indentation of a bulk metallic glass

The influence of hydrogen on the plastic deformation of bulk metallic glasses (BMGs) was analyzed by recourse to nanoindentation of subsurface deformation produced during macroscopic indentation of the as-cast and hydrogen-charged samples. Results reveal that hydrogen restricts the plasticity (that is, shear band evolution) and thus significantly enhances hardness. The deformed regions of both the as-cast and hydrogen-charged samples exhibit plastic flow softening. This study demonstrates that the hydrogen affects the plastic deformation of BMGs in a manner that is similar to structural relaxation. This is due to the similar influence both of them have on reducing the free volume content.