Effects of Ce addition on the oxidation behavior of Ni-28W-6Cr superalloy

The oxidation behavior of Ni-28W-6Cr-(0-0.190 wt.%)Ce alloys at 850 o C was investigated. The addition of Ce significantly decreases the oxidation rate of the alloys and the thickness of the inner oxide scale when the Ce content is below 0.023 wt.%. Then the decrease slows down when the Ce content reaches 0.190 wt.% due to the consumption of Ce in the γ matrix caused by the formation of Ni-Ce phase. Ce is solid-soluted in the inner oxide NiWO 4 and replaces the Ni 2+ by Ce with the valence of +3 and +4, therefore, the formation of oxygen vacancies and oxygen diffusion are inhibited. • The oxidation kinetics of Ni-28W-6Cr alloy decreases with Ce addition. • Ce prefers to solid solute in the inner oxide NiWO 4 , not form Ce 2 O 3 or CeO 2 . • Ce 3+ and Ce 4+ replace Ni 2+ in NiWO 4 , hindering oxygen vacancies formation.