Evaluation of three kinds of MCrAlY coatings produced by electrospark deposition
(1. State Key Laboratory for Corrosion and Protection, Institute of Metal Research,
Chinese Academy of Sciences, Shenyang 110016, China;
2. Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029, China)
Chinese Academy of Sciences, Shenyang 110016, China;
2. Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029, China)
Abstract: Three kinds of MCrAlY coatings with different aluminum contents (5%, 8%, 12%) were prepared by electrospark deposition (ESD), their microstructure and oxidation behavior were studied by SEM and XRD. The results showed that the phase composition of the coatings changed from single γ-Ni to γ-Ni+β-NiAl hypoeutectic to γ-Ni+β-NiAl hypereutectic with increasing aluminum content, and their solidification morphologies changed from cluster of cellular structure to cellular dendrites to coarse dendrites with secondary arms. When exposed at 1000 °C, the coatings with higher Al content had a stronger tendency to form θ-Al2O3 in the initial several hours. After 100 h of oxidation, a dense and adherent α-Al2O3 scale formed on all of the three coatings but the thickness of α-Al2O3 scale and the amount of remaining θ-Al2O3 increased with increasing Al content. These results revealed different characteristics of ESD MCrAlY coatings which could provide scientific guidance for industrial application.
Key words: MCrAlY; electrospark deposition; microstructure; oxidation behavior