AFM Observations of Deformation Mechanisms In Metallic Nanolaminates

Nanolaminate materials can exhibit very high strengths and toughness but the exact strengthening and toughening mechanisms are not yet fully understood. It is thought that the change in mechanical behavior at the layer interfaces affects dislocation motion, crack tip geometry and crack bridging, thereby increasing the strength and fracture toughness of the materials. In this study the mechanical behavior of electrodeposited nanolaminate nanocrystalline alloys with alternating Ni-rich and Cu-rich layers were examined. The effects of layer thicknesses and thickness ratios on microscale mechanical behavior as compared to monolithic specimens are presented. SEM, AFM and XRD were used to characterize the structure-property relationships. The high spatial resolution of the AFM facilitated the study of the effect of nanolaminate structure on deformation mechanisms. It is thought the thin ductile Cu-rich layers reinforce the Ni-rich layers.