High-temperature oxidation behavior of β-NiAl with various reactive element dopants in dry and humid atmospheres

• Oxidation of reactive elements doped NiAl in humid atmosphere was studied.
• Dy and La were prone to precipitate and form reactive-element rich oxides.
• Zr segregated at the scale/alloy interface to form numerous oxide pegs.
• Water vapor promoted the internal oxidation for Dy and La doped NiAl.

Oxidation behavior of NiAl alloys modified by various reactive elements (REs) were investigated at 1100 °C in dry and humid atmospheres, respectively. Among the doped alloys, the Zr-doped alloy showed similar oxidation behavior compared with the Hf-doped alloy, while the Dy and La doped alloys revealed poor oxidation resistance. Compared to Hf and Zr, Dy and La were prone to precipitate and form RE-rich oxides due to relatively low solubility. Zr ions segregated at the scale/alloy interface to form fine oxide pegs. For Dy and La NiAl alloys, water vapor promoted the internal oxidation, resulting in loss of protection.