The effect of the MCrAlY composition and aluminizing cycle upon the microstructure and hot corrosion resistance of the over‐aluminized MCrAlY coating on IN738LC alloy substrate

Abstract The aluminizing behavior of high‐velocity oxy‐fuel sprayed CoNiCrAlY, or NiCoCrAlY‐coated IN738LC alloy has been investigated via asingle or two‐step pack cementation aluminizing processes. The microstructural study showed that a more desirable low aluminum‐containing MCrAlY coating is obtained through single‐step aluminizing. The resultant over‐aluminized coating microstructure consisted of the Co‐containing beta‐NiAl in the aluminide top layer and the Ni−Co−Cr‐based austenitic gamma solid solution matrix decorated with the Co‐containing beta‐NiAl islands in the MCrAlY zone.