Fatigue-induced interface damage in Cu/V nanoscale metallic multilayers

The mechanism of fatigue-induced interface damage in Cu/V nanoscale metallic multilayers was systematically investigated using the state-of-the-art in situ transmission electron microscopy. Upon cyclic compression, Cu/V nanoscale metallic multilayers show an interface-controlled fatigue deformation, and the interface morphology of Cu/V nanopillars changes significantly after 200 cyclic loadings. Cyclic deformation induced nanoscale intrusions/extrusions on the bimetal interface, while no sign of persistent slip bands or crack was observed. Formation of the nano-intrusions/extrusions can be attributed to the reciprocating defect motion and severe defect-interface interactions during the fatigue testing. This study provides a unique mechanistic understanding on the fatigue damage in metallic multilayers at nanoscale and sheds light on tailoring the damage tolerance of heterostructures via interface engineering.