Deformation behavior of Al-rich metallic glasses under nanoindentation

To clarify the deformation behavior of Al-rich metallic glasses（MGs）, two kinds of Al-rich MGs（i.e. bulk and ribbon samples） with different frozen-in excess volume have been analyzed under nanoindentation.It was found that, with the decrease of frozen-in excess volume, the serration behavior becomes inconspicuous together with the increase of hardness. Further, shear transformation zones（STZs）, related to the occurrence of shear banding, have been evaluated by different methods: the cooperative shearing model（CSM）, the rate-jump method（RJM） and the dynamic-mechanical response（DMR）. In contrast,the STZ volumes, calculated by the RJM, increase from 2.77 nm;in the bulk to 3.59 nm;in the ribbon,which are in good agreement with 2.60 nm;obtained from the icosahedral supercluster medium-range order structure model in Al-rich MGs. This result reflects that an intrinsic correlation exists between the formation of STZs and the medium-range orders（MROs）. Moreover, the variation trend of the STZ volume was analyzed in terms of the frozen-in excess volume content.