Qualitative evaluation of failure mechanisms of aluminium 6061-T6 cold spray repairs

• Cold spray repairs show distinct failure modes at high and low pressure. • Adhesive and cohesive failures depend on processing parameters and bond strength. • SEM and DIC analyses revealed the failure characteristics. • Improved process specifications are needed to avoid unexpected failure modes. Cold spray is an emerging technology that shows great promise for the repair of civil aircraft components. However, certification of such repairs requires a comprehensive evaluation of repair performance, including a detailed assessment of repair strength and the associated failure mechanisms. The present research compared the failure mechanisms of cold-spray repaired specimens manufactured from aluminium alloy 6061-T6, produced using either a high-pressure or a low-pressure cold spray system, in tensile tests. Depending on the manufacturing process used, different failure mechanisms were observed, including cohesive failure of the deposit and failure of the deposit-substrate interface. The study suggests that failure in cold spray repair is driven by competing mechanisms, with the dominant mode influenced by both the applied load and the processing parameters, as well as the characteristics of the deposited material.