Cu/Zr nanoscaled multi-stacks fabricated by accumulative roll bonding

Abstract

In this paper, six pure Cu (99.96 mass%) and five pure Zr (99.8 mass%) sheets with overall composition of Cu 62Zr 38 (at%) were alternatively stacked and severely deformed up to equivalent strain ( ɛ) of 14.4 by accumulative roll bonding (ARB) technique at ambient temperature. During the ARB process, every individual Cu and Zr sheet in the multi-stacked materials decreases greatly in thickness with the increase of ɛ. Finally, nanolamellar structure with single layer thickness of about 20 nm can be obtained in the ARB processed Cu/Zr multi-stacks. Tensile tests were used to evaluate the mechanical properties of the ARB processed Cu/Zr multi-stacks related to the variations of ɛ. It reveals that the tensile strength increases greatly from 570 MPa at ɛ = 1.6 to 1210 MPa at ɛ = 14.4. However, the plastic elongation first increases from 8% at ɛ = 1.6 to 14% at ɛ = 9.6 and then decrease to 6% at ɛ = 14.4. The equivalent strain dominated microstructural evolution and deformation behavior of the ARB fabricated multi-stacks were put forward and discussed.