Layer thickness dependent strain rate sensitivity of Cu/amorphous CuNb multilayer

Abstract

Strain rate sensitivity of crystalline materials is closely related to dislocation activity. In the absence of dislocations, amorphous alloys are usually considered to be strain rate insensitive. However, the strain rate sensitivity of crystalline/amorphous composites is rarely studied, especially at nanoscale. In this study, we show that the strain rate sensitivity of Cu/amorphous CuNb multilayers is layer thickness dependent. At small layer thickness (below 50 nm), the multilayers demonstrate limited strain rate sensitivity; at relatively large layer thickness (above 100 nm), the strain rate sensitivity of multilayers is close to that of the single layer Cu film. Mechanisms that lead to size dependent variation of strain rate sensitivity in these multilayers are discussed.