Heat treatment of cold spray coatings to form protective intermetallic layers

A new technique for generating thick Mg/Al intermetallic coatings on Mg–Al–Zn alloys through post-spray annealing of aluminium cold spray coatings is discussed. Annealing at 400 °C, which is close to the solution treatment temperature for AZ91 alloy, results in the formation of thick Mg17Al12 and Al3Mg2 intermetallic layers. These layers have high hardness, and increase the corrosion resistance to a level similar to that of aluminium alloys.