Hot Corrosion Behavior of a New Nickel-Based Superalloy TROPEA

This paper reports on the hot corrosion behavior of the nickel-based single crystal superalloy TROPEA exposed to a deposit of Na 2 SO 4 in air and in SO 2 -containing atmospheres at 700 °C and 900 °C for 24 hours. In the absence of SO 2 , TROPEA simply oxidizes at 700 °C despite the Na 2 SO 4 deposit but the latter induces basic fluxing of protective oxides at 900 °C by developing NaTaO 3 and Na 2 CrO 4 phases. Yet, no specific role of Pt is found. In the presence of SO 2 , Pt is shown to enhance hot corrosion at low temperatures through a potential catalytic effect. However, Pt does not seem to exert any specific role at high temperature under the same gas atmosphere. Instead, Cr and Ta develop sulfides that foster the ingress of S into the material. Overall, TROPEA seems to behave similar to other SX superalloys except at low temperature where Pt appears to be particularly detrimental.