Combination of surface nanocrystallization and co-rolling: creating multilayer nanocrystalline composites

This paper presents a combination of the surface mechanical attrition treatment (SMAT) and the corolling process performed at 550 °C. This duplex method leads to the formation of a semi-massive multilayer structure of alternating nanocrystalline layers, transition layers and coarse grain layers. Transmission electron microscope observations correlated with nanoindentation hardness measurements demonstrated that grain size in the nanoand sub-nanocrystalline layers is preserved after the process. Tensile tests showed improved yield and ultimate strengths, and acceptable ductility.