| Abstract Scope |
Mo-based alloys are promising materials for gas turbines due to their high melting point, oxidation behavior, and mechanical strength at elevated temperatures. However, sulfate-rich combustion environments can trigger hot corrosion. Type I hot corrosion behavior of three new Mo-based alloys (Mo-9.0Si-8.0B, eutectic Mo-20.0Si-52.8Ti, and eutectoid Mo-21.0Si-34.0Ti, at.%) was investigated at 900°C for 24, 50, and 100 hours and analyzed by optical and electron microscopy, EPMA, and XRD.
Findings reveal a fluxing-based attack mechanism induced by a negative solubility gradient. At 24 hours, Mo-9.0Si-8.0B alloy had an oxide scale three times thicker than that of the eutectic alloy, which remained stable even after 100 hours due to its high Ti content, demonstrating superior type I hot corrosion behavior. Similarly, Si and Ti additions hindered the formation of volatile MoOx in the Mo-Si-Ti alloys with their mixed oxide layer consisting of TiO2 and SiO2. |