Role of Re additions on hot corrosion behaviors of a Co–Al–W superalloys

The hot corrosion behaviors of Co–Al–W superalloys with Re additions were investigated at 900 °C. The results showed that the addition of Re improved the hot corrosion resistance significantly. The alloys developed multi-layer oxidation and corrosion products, which located from surface to substrate were: the CoO and Co3O4 layer, the CoWO4 and CoAl2O4 layer, the Al2O3 layer, and the Co3W layer. The addition of Re promotes the formation of the α-Al2O3 scale, which is stable and dense. The thickness the α-Al2O3 scale in 1Re alloy is 1.9 μm, which is much thicker than that of the base alloy. The well-developed α-Al2O3 scale leads to the improvements in hot corrosion resistance.