Microstructural Evolution and Mechanical Behavior of Cu/Nb Multilayer Composites Processed by Accumulative Roll Bonding

Cu/Nb multilayer composites with minimum individual layer thicknesses of ≈2.8 μm are achieved by accumulative roll bonding (ARB). The microstructural evolution and mechanical properties of these composites are investigated with different layer thicknesses after ARB processing. The results show that there is no visible interfacial reaction between the Cu and Nb layers, and the kernel average misorientation (KAM) distributions in electron backscatter diffraction (EBSD) maps remain in steady state during the third to seventh ARB cycles. The tensile testing results demonstrate that the yield strength increases with decreasing layer thickness in Cu/Nb multilayer composites. A simultaneous increase of strength and elongation is achieved by regulating the laminated structures. Microstructure and fracture analysis indicate that the simultaneous increase of strength and elongation is attributable to the high density of bimetal interfaces, which act as a barrier for dislocation mobility and crack propagation.