Shear shuffling governs plastic flow in nanocrystalline metals: An analysis of thermal activation parameters

M. Grewer and R. Birringer
Phys. Rev. B 89, 184108 – Published 20 May 2014

Abstract

From strain-rate- and temperature-dependent deformation studies on nanocrystalline PdAu alloys with grain sizes 10 nm, the shear activation volume (6 b3), strain-rate sensitivity (0.03), as well as the Helmholtz (0.9 eV) and Gibbs free energy of activation (ΔG=0.2 eV) have been extracted. The close similarity to values found for metallic glasses indicates that grain boundary mediated shear shuffling dominates plasticity at the low end of the nanoscale. More fundamentally, we find that the energy barrier height exhibits universal scaling behavior ΔGΔτ3/2, where Δτ is a residual load, giving rise to a generalization of the Johnson-Samwer T2/3 scaling law of yielding in metallic glasses.

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  • Received 25 June 2013
  • Revised 31 March 2014

DOI:https://doi.org/10.1103/PhysRevB.89.184108

©2014 American Physical Society

Authors & Affiliations

M. Grewer* and R. Birringer

  • Experimentalphysik, Universität des Saarlandes, Saarbrücken, Germany

  • *m.grewer@mx.uni-saarland.de

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Issue

Vol. 89, Iss. 18 — 1 May 2014

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