Constitutive Behavior of Bulk Metallic Glass Composites at Ambient and High Temperatures

Abstract

When certain molten metallic alloys are rapidly quenched, they solidify to yield a disordered microstructure, called a metallic glass. Metallic glasses are generally brittle at room temperatures and fail catastrophically via one dominant or multiple shear bands. These limitations can be overcome by producing BMG composites, which contain crystalline phases, resulting in an increase in ductility and reduction of catastrophic failure. BMG composites fall into two categories: intrinsic (in-situ) and extrinsic (ex-situ). This study develops a three-dimensional constitutive description of (in-situ) BMG composites at room and high temperatures, and different strain rates, based on the second law of thermodynamics, finite-deformation theory and experimental data. A La-based in-situ BMG composite is the material investigated, and its response to compression at different strain rates examined. Experimental results are used to determine the material parameters in the constitutive description, while computational simulation is employed to predict the material stress-strain response.