Microstructure and corrosion performance of a cold sprayed aluminium coating on AZ91D magnesium alloy

A pure Al coating was deposited on AZ91D magnesium alloy through cold spray (CS) technique. The microstructure of the coating was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the grain interfaces and subgrains formed close to the particle/particle boundaries. Electrochemical tests revealed that the cold sprayed pure Al coating had better pitting corrosion resistance than bulk pure Al with similar purity in neutral 3.5 wt.% NaCl solution. In addition, a mass-transfer step was found to be involved in the corrosion during 10 days immersion.