Constitutive description of Bulk Metallic Glass composites at high homologous temperatures

Experimental stress–strain responses of La-based in situ Bulk Metallic Glass (BMG) composites within the supercooled liquid region reveal initial post-yield hardening, followed by softening and subsequent strain-hardening. This behavior contrasts with that of monolithic La-based BMGs, which reach a steady stress level after an initial overshoot. XRD analysis of BMG composites shows the formation of intermetallic compounds during compressive deformation. These intermetallic compound formation/interactions are associated with storage of energy in the material and affect the stress–strain response. In this study, an elastic–viscoplastic, three-dimensional, finite deformation constitutive model is also established to describe the behavior of a recently developed La-based in situ BMG (La–Al–Cu–Ni) composite, within the supercooled liquid region, at ambient pressure and a range of strain rates. The constitutive model is incorporated into a finite element program (ABAQUS/Explicit) via a user-defined material subroutine. Numerical predictions are compared with compression test results on BMG composites cast in-house. The comparison shows that the model is able to describe the material behavior observed.