Transition from stress-driven to thermally activated stress relaxation in metallic glasses

J. C. Qiao, Yun-Jiang Wang, L. Z. Zhao, L. H. Dai, D. Crespo, J. M. Pelletier, L. M. Keer, and Y. Yao
Phys. Rev. B 94, 104203 – Published 21 September 2016
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Abstract

The short-range ordered but long-range disordered structure of metallic glasses yields strong structural and dynamic heterogeneities. Stress relaxation is a technique to trace the evolution of stress in response to a fixed strain, which reflects the dynamic features phenomenologically described by the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation describes a broad distribution of relaxation times with a small number of empirical parameters, but it does not arise from a particular physically motivated mechanistic picture. Here we report an anomalous two-stage stress relaxation behavior in a Cu46Zr46Al8 metallic glass over a wide temperature range and generalize the findings in other compositions. Thermodynamic analysis identifies two categories of processes: a fast stress-driven event with large activation volume and a slow thermally activated event with small activation volume, which synthetically dominates the stress relaxation dynamics. Discrete analyses rationalize the transition mechanism induced by stress and explain the anomalous variation of the KWW characteristic time with temperature. Atomistic simulations reveal that the stress-driven event involves virtually instantaneous short-range atomic rearrangement, while the thermally activated event is the percolation of the fast event accommodated by the long-range atomic diffusion. The insights may clarify the underlying physical mechanisms behind the phenomenological description and shed light on correlating the hierarchical dynamics and structural heterogeneity of amorphous solids.

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  • Received 20 May 2016
  • Revised 22 August 2016

DOI:https://doi.org/10.1103/PhysRevB.94.104203

©2016 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Physical Systems
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

J. C. Qiao1, Yun-Jiang Wang2,3,*, L. Z. Zhao4, L. H. Dai2,3, D. Crespo5, J. M. Pelletier6, L. M. Keer7, and Y. Yao1,†

  • 1School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China
  • 2State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
  • 3School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
  • 4Institute of Physics, Chinese Academy of Science, Beijing 100190, China
  • 5Departament de Física, EETAC, Universitat Politècnica de Catalunya, 08860-Castelldfels, Barcelona, Spain
  • 6Université de Lyon, MATEIS, UMR CNRS5510, Bat. B. Pascal, INSA-Lyon, F-69621 Villeurbanne cedex, France
  • 7Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208, USA

  • *yjwang@imech.ac.cn
  • yaoy@nwpu.edu.cn

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Issue

Vol. 94, Iss. 10 — 1 September 2016

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