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arXiv · 1412.3044

Plastic yielding in nanocrystalline Pd-Au alloys mimics universal behavior of metallic glasses

A. Leibner·C. Braun·J. Heppe·M. Grewer·R. Birringer
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Abstract

We studied solid solution effects on the mechanical properties of nanocrystalline (NC) $\mathrm{Pd}_{\mathrm{100-x}} \mathrm{Au}_{\mathrm{x}}$ alloys ($0 \leq \mathrm{x} < 50 \mathrm{at.\%}$) at the low end of the nanoscale. Concentration has been used as control parameter to tune material properties (elastic moduli, Burgers vector, stacking fault energies) at basically unaltered microstructure (grain size $D\approx 10\mathrm{ nm}$). In stark contrast to coarse grained fcc alloys, we observe solid solution softening for increasing Au-content. The available predictions from models and theories taking explicitly into account the effect of the nanoscale microstructure on the concentration-dependent shear strength have been disproved without exception. As a consequence, it is implied that dislocation activity contributes only marginally to strength. In fact, we find a linear correlation between shear strength and shear modulus which quantitatively agrees with the universal behavior of metallic glasses discovered by Johnson and Samwer [W.L. Johnson and K. Samwer, PRL 95, 195501 (2005)].

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A. Leibner, C. Braun, J. Heppe, M. Grewer, R. Birringer. 2016-01-07. Plastic yielding in nanocrystalline Pd-Au alloys mimics universal behavior of metallic glasses. https://doi.org/10.1103/physrevb.91.174110

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