Outstanding 1200 °C Oxidation Resistance in a Novel Multi-Principal Element Alloy via Lattice Distortion-Induced Diffusion Suppression.

The ongoing demand for high-thrust turbine engines necessitates the advance of next-generation structural materials capable of withstanding higher temperatures. Commercial MCrAlY alloy, used as bond coats crucial for thermal barrier coating (TBC) systems, face a fundamental temperature ceiling of ∼1100 °C due to accelerated oxidation and spallation. Here, we design a novel Y and Hf co-doped NiCoCrAl-type multi-principal element alloy (MPEA) that achieves exceptional 1200 °C oxidation resistance primarily through lattice distortion-induced diffusion suppression. Compared with typical NiCoCrAlY alloy, the MPEA exhibits 59% lower in thermally grown oxide (TGO) growth rate, as well as negligible TGO spallation after 500 h at 1200°C. This performance stems from a significantly refined eutectic structure enabling rapid formation of a protective Al₂O₃ scale during initial oxidation, coupled with lattice distortion that elevates vacancy formation energy and Al migration barriers within the Al-depletion zone (ADZ), drastically reducing sustained diffusion rates. This co-design strategy, integrating tailored microstructure and lattice distortion, establishes a new paradigm for ultra-stable performance in extreme environments.