Investigation on Microstructure, Grain Refinement, and Mechanical Properties of Cu/AZ31/Cu Multilayered Composite Produced by Cross-Rolling Methods

Abstract

The positive effect of cross-rolling on the microstructure and mechanical properties of multilayered composites has received much attention in recent years. Therefore, in this paper, the Cu/AZ31/Cu multilayered composite has been fabricated by the cross-accumulative single-pass rolling method and the state-of-art process of cross-accumulative double-pass rolling. After each pass in these methods, the rolling direction was rotated anticlockwise. According to SEM images, all the layers were perfectly bonded without any obvious imperfections due to applying large strain and strain-path changes. Moreover, by increasing the cycles, the plastic instabilities increased in composites, although the ADPR method resulted in a more uniform reduction in AZ31 layer thickness and distribution of broken layers in the matrix. The line EDS analyses carried out on the interfaces of Cu/AZ31 did not show any interphases during the two methods. Furthermore, based on EBSD and TEM images, the grains were refined by both methods at higher cycles, although finer grains in Cu and AZ31 layers were obtained by the ADPR method. In addition, by increasing the cycles, the strength and hardness values of the composites increased. The composites processed by the ADPR process showed a tensile strength of 409 MPa and elongation of 17% which were higher than those achieved by the ASPR process. Similarly, the measured hardness of 213 HV (Cu) and 109 HV (AZ31) were achieved by the ADPR process, while lower values of the hardness of 209 HV (Cu) and 105 HV (AZ31) were achieved by the ASPR process.