Effect of Symmetric and Asymmetric Roll Bonding on Evolution of Microstructure and Mechanical Characteristics of Copper-Based Multilayered Composite

Abstract

The Cu/Zn/Cu composites were fabricated by symmetric accumulative roll bonding (SARB) and asymmetric accumulative roll bonding (AARB) processes. In the AARBed composite, more irregularities and better distribution of Zn were observed in the Cu matrix compared to the SARBed composite. Additionally, the Zn and Cu layers in the AARBed composite showed more evident grain refinement. Furthermore, employing the AARB process resulted in higher hardness over cycles. During AARB process, the hardness of Zn and Cu showed an increment of 23 HV and 117 HV between initial and final deformation cycles. Moreover, the AARBed composites showed higher strength values and lower elongation compared to the SARBed composites. The discrepancy between ultimate strength and elongation of AARBed and SARBed composites was 25 MPa and 3 pct after first deformation cycle, respectively, and reached 10 MPa and 1 pct after seventh deformation cycle. In addition, there was anisotropy of tensile results along rolling direction (RD) and transverse direction (TD). Higher strengths and elongation were measured along RD compared to TD. However, there was a reduction in anisotropy behavior from first deformation cycle to seventh deformation cycle.