Structure, wear and corrosion characterizations of Al/20wt.% Zn multilayered composites fabricated by cross-accumulative roll bonding

Abstract

In this study, Al/20 wt.% Zn laminated composites are produced by the cross-accumulative roll bonding (CARB) process. The microstructural, mechanical and corrosion characteristics of the composites are investigated at different passes of the CARB process. Using scanning electron microscopy, it is observed that during the CARB process, the Zn layers are necked, ruptured and gradually distributed in the Al matrix. Tensile testing results reveal that the incremental trend of strength stops unexpectedly at the sixth pass and then continues again at the higher passes, reaching 275 MPa at the eighth pass. The wear resistance of the samples increases up to the fourth pass, whereas it decreases gradually at the higher passes contrary to expectations. A mixed mode of abrasion, adhesion and delamination mechanisms is found to control the wear damage of the samples. The corrosion current density of the samples fabricated at the first pass is 3 times higher than the eighth pass, indicating the improvement of the corrosion resistance. Also, Nyquist plots show a single capacitance loop attributed to the formation of a passive film.