Microstructure and mechanical properties of AT31/ATX3105 magnesium alloy composite sheets fabricated by accumulative roll bonding

This study investigates the influence of accumulative roll bonding (ARB) cycles on the microstructure and room temperature (RT) mechanical properties of AT31/ATX3105 magnesium (Mg) alloy composite sheet. It is observed that, as the number of rolling passes increases, the interface between ATX3105 and AT31 layers exhibits stronger bonding. Furthermore, after five cycles of ARB treatment, the grain sizes of AT31 and ATX3105 layers are refined to ∼5.1 μm and ∼4.2 μm, respectively. With the increasing number of ARB passes, the strength of the composite sheets gradually increased, while their ductility showed a wave-like trend. It is particularly noteworthy that the ductility reached an optimal level of ∼17.0% after four ARB cycles. The composite sheet after five ARB cycles demonstrates the best comprehensive mechanical properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) at ∼ 205.4 MPa, ∼274.9 MPa and ∼15.4%, respectively. The strength improvement mainly comes from grain boundary strengthening and heterogeneous deformation-induced (HDI) strengthening due to the layered grain structure of alternating coarse and fine grains. The results of hetero-structured Mg alloy sheet produced by ARB provides a reference for the development of Mg alloy sheet with good mechanical properties.