Ductility of bulk metallic glasses and their composites with ductile reinforcements: A numerical study

Yield behavior of bulk metallic glasses containing voids is elucidated by using unit-cell analyses and the relevant material parameters; and the results are compared with the available constitutive models. These analyses clearly show that caution is needed when transferring the constitutive models associated with void growth and ductile damage in usual metallic materials to bulk metallic glasses, largely because of the different deformation modes in bulk metallic glasses resulting from the pressure dependency of the yield surface and intrinsic softening behavior. With the constitutive model calibrated from the unit-cell analysis, the influences of a wide range of parameters (mechanical properties, volume fraction and morphology of ductile reinforcements) on the ductility of metallic glass composites are explored. The results indicate that, even though the ductile reinforcements may alter the evolution and morphology of the shear bands, the overall failure behavior is still controlled by the metallic glass matrix, leading to very little or no improvement in the composite ductility in comparison to the ductility of metallic glass matrix. The results are compared with experimental studies available in the literature. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.