Tuning correlative atomic scale fluctuation and related properties in Ni-Nb-Zr metallic glasses

Abstract

Herein, we systematically investigated how to tailor correlative fluctuation and related properties in Ni-Nb-Zr metallic glasses (MGs). The Ni60Nb40-xZrx MGs (x = 0-20 at.%) with Nb-Zr atomic pair (Delta H-mix=+4 kJ/mot) exhibited correlative atomic scale fluctuations in composition and topological orders upon Zr addition up to 20 at.% in XAFS analysis, which would, in turn, lead to fluctuations in local elastic properties. Interestingly, a statistical analysis of strain burst sizes along with in situ bending test showed that more effective elastic interaction between weak spots upon loading is promoted in Ni60Nb20Zr20, due to correlative atomic scale fluctuations, thereby resulting in multiple shear bands. The bulk specimens (d =1 mm) for 8 and 10 at.% of Zr with increased glass -forming ability (GFA) exhibited enhanced plasticity without the reduction of fracture strength, implying cooling rate effect on fluctuation-induced plasticity. We believe that the results of this study would provide an effective guideline for tuning correlative fluctuation and related properties in MGs via manipulation of enthalpy relationship and cooling rate. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.