Oxidation resistance and thermal stability of a β-solidified γ-TiAl based alloy after nitrogen ion implantation

•β-solidifying TiAl-based alloy subjected to N ion implantation with low (40 keV) energy.•TiN, Ti2N, Ti3AlN, and Ti3Al2N2 particles nitrides formed in the modified layer.•Annealing at 550 or 750 °C resulted in dissolution of the Ti2N phase.•N ion implantation significantly enhanced oxidation resistance of the alloy.•Thin, continuous, and stable oxide layer is formed during oxidation tests. Oxidation behavior and thermal stability of a β-solidifying γ-TiAl alloy after plasma source nitrogen ion implantation were studied. Nano-sized TiN, Ti2N, Ti3AlN, and Ti3Al2N2 particles were found in the modified layer. The microhardness of the modified layer was 2.5 times higher than that of the as-cast condition. Nitrogen ion implantation increased the oxidation resistance significantly in comparison to the as-cast condition. Thin inner and outer TiO2, dense protective Al2O3 and fine-grained mixed Al2O3+TiO2 layers were found on the surface after oxidation. The effect of nitrogen ion implantation on phase stability and oxidation mechanisms is analyzed.