Inhibition mechanism of cold sprayed Al-based composite repairs on micro-galvanic corrosion in a cast magnesium alloy substrate

Cold spraying (CS) is a rapid and solid-state additive manufacturing technique that shows significant promise for repairing damaged magnesium alloy components. This study systematically investigates the micro-galvanic corrosion inhibition mechanism and the redistribution of corrosion behavior after heterogeneous CS aluminum-based composite repairs on a cast ZM6 substrate. The strong cathode introduced by the CS repair suppresses the micro-galvanic corrosion of precipitates as a weak cathode in ZM6 alloy. However, when the repair area ratios exceed 20%, the enlarged effective contact area exacerbates the corrosion of the ZM6 substrate. Furthermore, the addition of Al₂O₃ ceramic particles as a reinforcing phase enhances the density of the repair zone, inhibits the inward diffusion of corrosive media, and reduces the effective exposed area, thereby improving the corrosion resistance. This work provides a very valuable insight for developing and evaluating cold sprayed repairs for damaged magnesium alloy components.