title: Structural Signature of Plasticity Unveiled by Nano-Scale Viscoelastic Contact in a Metallic Glass.
abstract: Room-temperature plasticity in metallic glasses (MGs) is commonly associated with local structural heterogeneity; however, direct observation of the subtle structural change caused by plasticity is vitally important but the data are extremely scarce. Based on dynamic atomic force microscopy (DAFM), here we show that plasticity-induced structural evolution in a Zr-Ni MG can be revealed via nano-scale viscoelastic contacts between an AFM tip and plastically deformed MG surface layers. Our experimental results clearly show a spatial amplification of the nano-scale structural heterogeneity caused by the distributed plastic flow, which can be linked to the limited growth, reorientation and agglomeration of some nano-scale energy-absorbing regions, which are reminiscent of the behavior of the defect-like regions with non-affine deformation as conceived in many theories and models. Furthermore, we are able to experimentally extract the thermodynamic properties of these nano-scale regions, which possess an energy barrier of 0.3-0.5 eV, about half of that for a typical shear transformation event that usually occurs at the onset of plasticity. The outcome of our current work sheds quantitative insights into the correlation between plasticity and structural heterogeneity in MGs.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.|Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: Y M
authors.initials: YM
authors.lastname: Lu
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: J F
authors.initials: JF
authors.lastname: Zeng
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: B A
authors.initials: BA
authors.lastname: Sun
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.affiliation: Université de Grenoble, CNRS, SIMAP Laboratory, UJF, Grenoble INP, BP46, 38402 Saint-Martin d'Hères, France.
authors.forename: S
authors.initials: S
authors.lastname: Gravier
authors.affiliation: Université de Grenoble, CNRS, SIMAP Laboratory, UJF, Grenoble INP, BP46, 38402 Saint-Martin d'Hères, France.
authors.forename: J J
authors.initials: JJ
authors.lastname: Bladin
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: W H
authors.initials: WH
authors.lastname: Wang
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: M X
authors.initials: MX
authors.lastname: Pan
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: C T
authors.initials: CT
authors.lastname: Liu
authors.affiliation: Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang