Evolution of mechanical properties in SPD processed Cu/Nb nano-layered composites

摘要

Cu/Nb nano-layered composite with three different Nb. vol. fractions of 15.6%, 25%, and 36.3% was produced using "Repeated Press and Rolling" technique via two different strain routes. It was observed that UTS of samples increases with processing strains and experiences a sharp rise at the latest pass where the thickness of individual layers reaches the nano-scale. It was illustrated that the higher rolling speed within the Repeated Press and Rolling processing results in decreased UTS values. UTS values for three-pass strain route also appeared to be in better conformity with Rule of Mixtures in comparison with five-pass strain route which considerably exceeds the ROM predicted UTS values. The rate of UTS increasing with respect to Nb. vol. fraction was also observed to be considerably higher in the latest pass of processing than intermediate passes. Elongation of samples appeared to increase with induced processing strain which was attributed to the high density of dislocations as well as deformation and growth twins. It denotes that the processing method of Repeated Press and Rolling for Cu/Nb composite results in laminates with simultaneous increasing of strength and ductility.