Modeling of extremely ductile behavior of Zr-based bulk metallic glasses under compressive strain paths for solid-state processing

International audienceIn addition to extremely high strength, manufacturing temperaturesof bulk metallic glasses (BMGs) relative to steels are low makingthem to desired energy saving engineering materials. However, BMGsare significantly brittle at low temperatures. To further increasesuitability of BMGs for widespread use, it is essential tounderstand their plastic deformability (ductility) for high-techsolid-state processes at lowered temperatures. In this work,extremely large deformation behavior (near 80% in compression) ofindustrially important Zr-based BMGs was investigated. Theexperimentally measured results aided in the development of anappropriate constitutive model and revealed the micromechanismsaffecting the characteristic macroscopic deformation behaviorincluding softening and hardening. The measured and model resultsshowed that the ductility can be significantly improved throughchemical composition changes, such as a reduction in the Cu contentand an increase in the Zr, Ti, or Be contents. In contrast topreviously announced conclusions on the high glass-forming ability(GFA) being the precursors to ductility, formation of sufficientlylow degree of crystallization during cooling improved ductility ofas-cast specimens under loadings. These observed properties areimportant in assessing the ability of BMGs for solid-stateprocessing