Nanoscale creep deformation in Zr-based metallic glass

• Nanoscale creep deformation in Zr61Al7.5Cu17.5Ni10Si4 was investigated via nanoindentation.
• The effects of applied strain rate and initial creep depth on the creep deformation were evaluated.
• A critical penetration depth was identified, below which creep behavior was strain rate dependent.
• Interface diffusion dominates at shallow depth while surface effect is negligible at deep depth.

Nanoscale creep deformation in Zr61Al7.5Cu17.5Ni10Si4 thin films was investigated via instrumented nanoindentation testing. Over three decades of indentation strain rate with varying penetration depth were used to evaluate the effects of applied strain rate and initial creep depth on the creep deformation within small volumes of the metallic glass. A critical penetration depth was identified, below which the creep deformation was dependent upon the applied strain rate, and above which the strain rate sensitivity of the creep deformation reached a plateau value. It was proposed that an interface diffusion mechanism dominated the creep deformation within the shallow depth regime, whilst a transition from the interface diffusion dominant mechanism to the intrinsic creep behavior of the Zr-based metallic glass occurred within the deep depth regime.