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|Title:||On the evolution of free volume during the deformation of metallic glasses at high homologous temperatures|
|Citation:||Ekambaram, R., Thamburaja, P., Nikabdullah, N. (2008-06). On the evolution of free volume during the deformation of metallic glasses at high homologous temperatures. Mechanics of Materials 40 (6) : 487-506. ScholarBank@NUS Repository. https://doi.org/10.1016/j.mechmat.2007.11.005|
|Abstract:||Recently a finite-deformation and coupled thermo-mechanically-based theory for metallic glasses has been developed by Thamburaja and Ekambaram [Thamburaja, P., Ekambaram, R., 2007. Coupled thermo-mechanical modelling of bulk-metallic glasses: theory, finite-element simulations and experimental verification. J. Mech. Phys. Solids 55, 1236-1273], and implemented in the ABAQUS/Explicit (2007) finite-element program. In this work, we use the aforementioned constitutive model and its numerical algorithm to study the deformation behavior of a Pd-based metallic glass near its glass transition temperature. At a temperature of 564 K, the material parameters in the constitutive model were fit to the simple tension stress-strain curves and the steady-state free volume concentrations data for a variety of applied strain-rates obtained from De Hey et al. [De Hey, P., Sietsma, J., Van Den Beukel, A., 1998. Structural disordering in a amorphous Pd-Ni-P induced by high temperature deformations. Acta Mater. 46, 5873-5882]. With the model calibrated, the simple tension steady-state stresses and free volume concentrations data for a variety of applied strain-rates at temperatures of 556 K and 549 K (De Hey et al.) were predicted to be in good accord by the constitutive model. Furthermore, the experimental stress-strain curves for samples annealed for different times before the tensile tests were carried out under a particular strain-rate (De Hey et al.) were also well-predicted by the constitutive model. Finally we also perform numerical simulations to show that at a given temperature below the glass transition temperature, metallic glasses which show shear localization behavior as a result of being tested in the fully-annealed condition can be made to deform more homogeneously by first pre-deforming the specimen under high strain-rates at temperatures within the supercooled liquid region before being tested again at temperatures below the glass transition temperature. © 2007 Elsevier Ltd. All rights reserved.|
|Source Title:||Mechanics of Materials|
|Appears in Collections:||Staff Publications|
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