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

This paper describes a combination of surface mechanical attrition treatment and co-rolling 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-grained layers. Transmission electron microscopy observations correlated with nanoindentation hardness measurements demonstrate that the nano- and subnanocrystalline layers are preserved after the process. Tensile tests showed improved yield and ultimate strengths, and acceptable ductility.