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Title: Inhomogeneous thermal expansion of metallic glasses in atomic-scale studied by in-situ synchrotron X-ray diffraction

Numerous investigations have demonstrated that the elastic strain in metallic glasses subjected to mechanical loading could be inhomogeneous in the atomic-scale and it increases with distance from an average atom and eventually reaches the macroscopic strain at larger inter-atomic distances. We have observed a similar behavior for the thermal strain imposed by heating of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy particles below the glass transition temperature by analysis of the scattering data obtained by in-situ high-energy synchrotron X-ray diffraction (XRD). The results imply that the volumetric thermal strains calculated from the shift in position of the principal diffraction maximum and reduced pair correlation function (PDF) peaks are in good agreement for the length scales beyond 0.6 nm, corresponding to the atoms located over the third near-neighbor shell. However, smaller and even negative volumetric thermal strains have been calculated based on the shifts in the positions of the second and first PDF peaks, respectively. The structural changes of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy particles are accompanied by decreasing the average coordination number of the first near-neighbor shell, which manifests the occurrence of local changes in the short-range order upon heating. It is believed that the detected length-scale dependence of the volumetricmore » thermal strain is correlated with the local atomic rearrangements taking place in the topologically unstable regions of the glass governed by variations in the atomic-level stresses.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4]
  1. Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of)
  2. IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden (Germany)
  3. Photon Science DESY, Notkestraße 85, 22603 Hamburg (Germany)
  4. (Germany)
Publication Date:
OSTI Identifier:
22413006
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COORDINATION NUMBER; CORRELATION FUNCTIONS; ELASTICITY; GLASS; METALLIC GLASSES; STRAINS; STRESSES; SYNCHROTRON RADIATION; THERMAL EXPANSION; TRANSITION TEMPERATURE; VARIATIONS; X-RAY DIFFRACTION