Interpreting size effects of bulk metallic glasses based on a size-independent critical energy density

Sample-size effects on compressive deformation behavior have been carefully studied for several bulk amorphous alloy systems. The yielding strength is almost unchanged for all sized samples but the compressive plasticity is increased with the decrease of the sample sizes. It was found that there existed a critical plane energy density above which the catastrophic fracture would occur. This critical energy density is dependent on the composition of the glassy samples but independent of the sample sizes. Large samples reach the critical plane energy density within much smaller strain, thus resulting in the observed size-dependence of the macroscopic plasticity.