Regulating TGO Nucleation and Growth of MCrAlX Coatings via Femtosecond Laser Remelting: The Role of Reactive Elements in the Oxidation Resistance AITranslate

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MCrAlX coatings are widely used as bond coats in thermal barrier coating systems to protect turbine blades from high-temperature oxidation. However, their oxidation resistance is often restricted by uncontrolled microstructures, surface roughness, and aggregation of reactive elements (REs). In this study, high-repetition-rate femtosecond laser remelting (HRR-FLR) is introduced as an advanced surface modification technique to overcome these limitations. Owing to its ultrafast self-quenching and polishing effects, HRR-FLR enables precise control of surface morphology, microstructural reconstruction, and REs redistribution. As a result, a uniform and periodic distribution of REs is achieved, which promotes the rapid nucleation and compact growth of α-Al2O3 and helps maintain the stability of the oxide scale under long-term exposure. The HRR-FLR-treated coatings show remarkable performance, with the TGO growth rate reduced by approximately 80% and the oxidation lifetime extended to about 300 h compared with the untreated ones. Moreover, REs exhibit a dual function during oxidation: They act as preferential nucleation sites for Al2O3 in the initial stage and segregate at TGO grain boundaries during growth, thereby suppressing outward cation diffusion. Overall, HRR-FLR provides a novel and effective femtosecond-laser-based approach to tailor REs’ behavior and enhance the long-term oxidation resistance of MCrAlX coatings, offering practical insights for the design of high-temperature protective systems.