Enhancement of glass-forming ability and plasticity via alloying the elements having positive heat of mixing with Cu in Cu48Zr48Al4 bulk metallic glass

Abstract Limited glass-forming ability (GFA) and room-temperature brittleness are currently critical challenges for the field of bulk metallic glasses (BMGs). Simultaneously enhancing GFA and plasticity is a central yet important research theme in this area. In contrast to the traditional wisdom, herein we report that addition of the elements with positive heat of mixing (PHM) into Cu-Zr-Al BMGs not only facilitated glass formation but also enhanced plasticity. It was found that the elements with a smaller PHM value have a larger optimal dose and are more effective in enhancing GFA due to stabilization of the liquid phase with an enhanced packing density and destabilization of the crystalline phase by slowing down the atomic rearrangement. Moreover, addition of the elements with a medium PHM value is beneficial for plastic deformation because of the enhanced structural heterogeneity. The established composition-GFA-properties relationship is useful for designing novel BMGs with both enhanced GFA and plasticity via alloying the PHM elements.