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.