An innovative and flexible approach to fabricate Mg/Al composite plates: Cold spraying and hot rolling post-treatment

Abstract

In this work, an innovative and flexible approach was used to fabricate Mg/Al composite plates. Instead of using ready-made Al alloy sheets, 7075 Al powder was directly deposited on AZ31B Mg plates by cold spraying (CS), resulting in well-bonded Mg/Al composite plates (As-Sprayed). The As-Sprayed composite plates were then subjected to hot rolling (HR) to further enhance the mechanical properties (As-Rolled). The interfacial microstructures, texture evolution, intermetallic compounds (IMCs) formation, mechanical properties and fracture behavior of the As-Sprayed and As-Rolled Mg/Al composite plates were systematically investigated both in the rolling direction (RD) and transverse direction (TD). The results showed that the mechanical properties of the Mg/Al composite plates (prepared by CS + HR) are comparable to or even better than those of their counterparts prepared by traditional roll bonding, explosive welding and diffusion bonding processes, etc. The As-Sprayed composite plates exhibited the highest shear bond strength due to the strong mechanical interlocking at the interface, which was induced by the CS process. The HR strengthened the bonding between Al–Al particles and resulted in grain refinement of AZ31B Mg layer. In addition, strip-distributed IMCs were formed at the interface of the HR sample. Consequently, the ultimate tensile strength (UTS) of the constituent Al and Mg sheets as well as the composite plate were increased, while the shear bond strength was slightly reduced. Moreover, the process of crack initiation and propagation in the composite plates was studied in detail to understand the fracture mechanism.