Impact of hydrogen microalloying on the mechanical behavior of Zr-bearing metallic glasses: A molecular dynamics study

Comparative studies on Zr₃₅Cu₆₅ and Zr₆₅Cu₃₅ amorphous systems were performed using molecular dynamic simulations to explore whether their hydrogenated mechanical behavior depends on the content of hydride-forming elements. Although both of them present an increased strength and ductility after hydrogen microalloying, we observe the improved mechanical behavior for Zr₃₅Cu₆₅ is more pronounced than that for Zr₆₅Cu₃₅. In these two samples, the distribution of configurational potential energy and flexibility volume respectively follows a similar H-induced variation tendency; all of the hydrogenated alloys not just have more stable atoms with smaller flexibility volume, but possess a larger fraction of readily activated atoms. However, the atomic-scale details, based on the local “gradient atomic packing structure” model, indicate minor additions of hydrogen can promote more “soft spots” along with more strengthened “backbones” in the low-Zr alloy than that in the high-Zr sample, which endows the former with much higher strength and deformability after hydrogen microalloying. We regard this finding as a further step forward to distilling the tell-tale metrics of the H-dependent mechanical behavior observed in Zr-based metallic glasses.