Effect Of Hydrogen On Mechanical Properties Of Zr-based Bulk Metallic Glasses

Metallic glasses have many loose atomic clusters and free volumes,which can provide potential hydrogen occupation and diffusion channels.They are a kind of potential hydrogen storage and permeation materials.In addition to the above properties,the mechanical properties of metallic glasses with different hydrogen contents should be paid attention to in practical application.However,there is still a lack of sufficient experimental data and mechanism research in this direction.Furthermore,hydrogen can also be used as a probe to study the microstructure and essence of metallic glasses.Therefore,the study of the interaction between hydrogen and metallic glasses has become another research direction in the field of metallic glasses.In this paper,taking Zr-based bulk metallic glasses as the research object,three typical bulk metallic glasses of Zr₅₅Cu₃₀Al₁₀Ni₅,Zr₆₄Cu₂₄Al₁₂ and Zr₆₆Cu₂₂Al₁₂ with different hydrogen contents were prepared by hydrogen argon plasma arc melting method.The effects of hydrogen on microstructure,nanoindentation deformation behavior,room temperature and high temperature compressive properties of Zr-based bulk metallic glasses were systematically studied,and the causes of their effects were further analyzed.The results showed that:?1?The hydrogenated alloy can still maintain a completely amorphous structure,and the addition of hydrogen increases the supercooled liquid region width of Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glasses by 6?.?2?With the addition of hydrogen,the Vickers hardness of Zr-based bulk metallic glasses decreases obviously and the shear bands around the indentation increase.The nanoindentation hardness and elastic modulus of Zr-based bulk metallic glasses also decrease significantly with the increase of hydrogen content.The nanoindentation load-displacement curve of Zr-based bulk metallic glasses with different hydrogen content shows serration flow phenomenon in different degrees.With the increase of hydrogen content,the number of steps on the curve decreases,the width decreases,and the serration flow phenomenon gradually weakens.From the perspective of shear band formation process,this effect is equivalent to the effect of indentation process with increasing loading rate.Zr-based bulk metallic glasses with different hydrogen contents show room temperature creep,and creep displacement and creep stress index increase with the increase of hydrogen content.The addition of hydrogen increases the activation energy,shear transition zone volume,atomic number and other internal rheological unit parameters of Zr-based bulk metallic glasses during nanoindentation loading and holding phases,indicating that the addition of hydrogen makes the interior of metallic glasses more“active”,promotes the inoculation and proliferation of shear zones,and facilitates plastic deformation.In addition,the increase of Zr content promotes this hydrogen-induced softening behavior,while the increase of component number delays it.?3?With the increase of hydrogen content,the room temperature plasticity of Zr55Cu30Al10Ni5 bulk metallic glasses is obviously improved,and the stress drop in its compressive serration flow gradually tends to stabilize within a small range,the vein pattern distribution in the corresponding fracture morphology gradually becomes tight,the lateral shear bands also increase,and the phenomena of mutual delivery,branching and blocking are obviously increased.?4?The thermal deformation behavior of Zr55Cu30Al10Ni5 bulk metallic glasses in supercooled liquid phase region is very sensitive to the change of hydrogen content.When the hydrogen content is 0.017 wt.%,hydrogen can significantly reduce the flow stress of the alloy,while when the hydrogen content exceeds 0.017 wt.%,the flow stress increases instead,which is caused by the local crystallization of the metallic glasses and the generation of nanocrystals.