Microstructure and hot corrosion behaviors of a γ-toughened Cr13Ni5Si2/Cr3Ni5Si2 ternary metal silicide alloy

The hot corrosion behaviors of a novel γ-toughened Cr13Ni5Si2/Cr3Ni5Si2 ternary metal silicide alloy were evaluated by corrosion kinetics and depths of corrosion attack in molten Na2SO4 + 25 wt.% K2SO4 at 900 °C. The surface and cross-sectional morphologies as well as microstructural change after hot corrosion were investigated by OM, SEM, XRD and TEM. Results showed that the metal silicide alloy was still at the initial stage of hot corrosion even after corroded at 900 °C for 120 h and neither characteristics of internal attack nor sulfides were detected in substrate. The excellent hot corrosion resistance can be attributed to the ultra-high Cr content in the alloy, guaranteeing the formation of a continuous and protective Cr2O3 layer during hot corrosion process.