Effect of Hydrogen Charging on Pop-in Behavior of a Zr-Based Metallic Glass

Lin Tian,Moritz Hirsbrunner,Tim Sievert,Zhiwei Shan,Dominik Tönnies,Cynthia A Volkert

doi:10.3390/met10010022

Lin Tian, Moritz Hirsbrunner + Show 4 more

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https://doi.org/10.3390/met10010022

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Journal: Metals	Publication Date: Dec 22, 2019
Citations: 9	License type: CC BY 4.0

Affiliation: University of Göttingen, Xi'an Jiaotong University

Abstract

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.

Highlights

Metallic glasses (MGs) or amorphous metals are materials composed of metal components but without crystalline structure [1]
Building on the model of Wang et al, we propose that hydrogen stabilization of shear transformation zones (STZs) decreases their density, thereby increasing the correlation length and hindering strain localization and pop-in instabilities
We further suggest that the high mobility of the hydrogen may allow it to change sites in response to changing strain fields, inhibiting propagation of excitations between STZs and hindering pop-in formation

Summary

Introduction

Metallic glasses (MGs) or amorphous metals are materials composed of metal components but without crystalline structure [1]. In addition to applications as high-performance structural materials [2], the unique structure of MGs makes them promising candidate materials in many other fields. As one of the important applications, MGs can be used as storage and separation media for hydrogen gas (H2 ), which is a well-known clean energy source. The high solubility and moderate diffusivity of hydrogen [5] in the amorphous structure increases. The performance and stability of MGs in H2 have significant impact on device safety, and the effects of hydrogen on the mechanical properties of MGs have received increasing attention

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