Accumulative roll bonding of multilayered Cu/Zn/Al: An evaluation of microstructure and mechanical properties

In the present study, multilayer Cu/Zn/Al was processed by accumulative roll bonding (ARB) up to 14 cycles. By using scanning electron microscopy and elemental mapping, necking and rupture of layers upon 4 and 5 cycles were detected. A uniform distribution of fragments was achieved after 14 cycles. The formation of intermetallic CuZn5 after 5 cycles was confirmed by X-ray diffraction. Microcracks were formed due to intermetallic formation at the interface and several cavities were observed in Zn layer. Results showed that the strength increased up to 290 MPa after 4 cycles and dropped afterward. Microhardness measurement indicated that hardness of individual layers increased continually with increasing the ARB cycle. Tensile fracture mode for Cu and Al layers was ductile at initial cycles and then changed to brittle at higher cycles. The fracture mode for Zn layer was brittle at all stages.