The use of kinetic metallization to form intermetallic reinforced composite coatings by post-spray heat treatment

Al + Ni coatings were deposited on AZ91 alloy substrates by cold spray in a fully dense state, with uniform dispersion of the two particle species. Post-spray heat treatment at 420 °C, which is compatible with the typical AZ91 heat treatment regime, leads to the formation of the NiAl3 and Ni2Al3 phases within the coatings. Therefore, metal matrix Ni–Al intermetallic reinforced composite coatings on AZ91 substrates can be readily obtained. Although the Kirkendall effect results in porosity, reducing heat treatment time or increasing the proportion of Al in the coating can significantly decrease pore size and fraction.