Influence of the Hydrogen Doping Method on the Atomic Structure, Mechanical Properties and Relaxation Behaviors of Metallic Glasses

The interaction of metallic glasses (MGs) with hydrogen can trigger many interesting physical, chemical and mechanical phenomena. However, atomic-scale understanding is still lacking. In this work, molecular dynamics (MD) simulations are employed to study the atomic structure, mechanical properties and relaxation behaviors of H-doped Ni50Al50 MGs doped by two methods. The properties of H-doped MGs are determined not only by the hydrogen content but also by the doping method. When H atoms are doped into the molten state of samples, H atoms can fully diffuse and interact with metallic atoms, resulting in loose local atomic structures, homogeneous deformation and enhanced beta relaxation. In contrast, when H atoms are doped into as-cast MGs, the H content is crucial in affecting the atomic structure and mechanical properties. A small number of H atoms has little influence on the elastic matrix, while the percolation of shear transformation zones (STZs) is hindered by H atoms, resulting in the delay of shear band (SB) formation and an insignificant change in the strength. However, a large number of H atoms can make the elastic matrix loose, leading to the decrease in strength and the transition of the deformation mode from SB to homogeneous deformation. The H effects on the elastic matrix and flow units are also applied to the dynamic relaxation. The deformability of H-doped Ni50Al50 MGs is enhanced by both H-doping methods; however, our results reveal that the mechanisms are different.

Automated summary

In this study, molecular dynamics simulations were used to investigate the effects of hydrogen doping on the atomic structure, mechanical properties, and relaxation behavior of H-doped Ni50Al50 metallic glasses. The properties of H-doped MGs were found to depend not only on the hydrogen content but also on the doping method. Doping H atoms into the molten state resulted in loose atomic structures, homogeneous deformation, and enhanced beta relaxation. On the other hand, doping H atoms into as-cast MGs affected the atomic structure and mechanical properties. A small number of H atoms had little impact on the elastic matrix, while a large number of H atoms caused a decrease in strength and a shift from shear band to homogeneous deformation.