Study on unsteady rolling cooperative deformation and interface behavior of Ti2AlNb/7075Al laminated metal composites

Ti2AlNb/7075Al laminated metal composites (LMCs) exhibit a low density, high strength, and outstanding mechanical properties under short-term elevated temperatures. They hold significant potential for application in aircraft operating across wide temperature range. However, the significant differences in mechanical properties and processing temperature between 7075Al and Ti2AlNb present challenges for fabricating LMCs using conventional manufacturing methods. Therefore, this study proposes an unsteady rolling method for fabricating the high-quality Ti2AlNb/7075Al LMCs. The interfacial bonding rate reaches 88 %. These LMCs with a density of 3 g/cm3 demonstrate excellent mechanical properties, achieving a tensile strength exceeding 650 MPa and an elongation greater than 16 %. Precise strength matching between Ti2AlNb and 7075Al is achieved during unsteady heat treatment at 650-700 degrees C for 1-3 min. Within this range, 7075Al shows no signs of over-burning and its tensile strength decreases by only 25 %. Meanwhile, Ti2AlNb does not experience hardening caused by Ophase precipitation and demonstrates excellent plasticity. This excellent mechanical property matching results in coordinated deformation of the two metals during the rolling process. A few Ti2AlNb grains undergo kinking to accommodate the deformation. The Ti2AlNb layer near the interface forms shallow rectangular tear gaps, which are filled by 7075Al, creating a strong mechanical interlocking. Meanwhile, the rapid rolling process prevents the formation of brittle products at the interface. Atomic scale bonding is observed at the interface of the Ti2AlNb/ 7075Al LMCs.