Kinetics and morphological study of hot corrosion of Rene 80 nickel based superalloy

In this work, to have a better understanding about failure mechanism and the effect of working conditions on aeroengine turbine blades made of Rene 80 nickel based superalloy, its hot corrosion behavior was studied. The alloy samples, after coating with sodium sulfate solution were cycled at 800, 850, 900 and 950°C by 5-hour cycles.Results showed that at 800 and 850°C, the propagation stage was not initiated and weight change followed a parabolic trend which its rate constant estimated 3.79 x 10-8 and 4.71 X 10-8 respectively. The propagation stage initiated at 900°C and the samples were destroyed after 4 cycles. MicrostructuraL phase and chemical analysis showed that the hot corrosion products of the samples were made of 3 layers. Upper layer consisted of compacted NiO, intermediate layer was porous NiO and the layer lied beneath was a mixture ofNiO + NiS resembled a honeycomb structure.