Effect of chemical composition on mechanical properties and shear band propagation in fully-amorphous ZrCu/ZrCuAl nanolaminates

Abstract

The mechanical behavior and propagation of shear bands (SBs) in fully amorphous ZrCu/ZrCuAl₉ nanolaminates with different nanoscale bilayer period (Λ, from 200 down to 50 nm) was investigated. The combined effect of local chemistry variation and nanointerface density influences the propagation of SBs and the mechanical behavior, reporting nanoindentation hardness values above the rule of mixtures, due to severe shear displacement and strong compositional intermixing along the SB-deformed zone with diffusion of Al into ZrCu layers. Enhanced plastic deformation (> 10 %) is observed for Λ = 100 and 200 nm during micropillar compression, but accompanied by a reduction of the yield strength. In contrast, for Λ = 50 nm, deformation is dominated by catastrophic SB events, while the yield strength returns to that of the monolithic films of ∼2–2.5 GPa. Our results can be utilized in design of nanostructured metallic glasses with tailored mechanical performance.