A study on the thermal cyclic behavior of NiCrAlY coatings via femtosecond laser remelting with high repetition rate

NiCrAlY coatings are widely applied bond coatings in thermal barrier coating systems to prevent high-temperature oxidation of turbine blades. However, the uncontrollable microstructure design and high surface roughness seriously affect the oxidation resistance. Herein, NiCrAlY coatings fabricated through arc ion plating were subjected to high-repetition-rate femtosecond laser remelting (HRR-FLR) treatment. This study assessed the surface rumpling behavior, residual stress evolution, and thermally grown oxide (TGO) layer growth under thermal cyclic oxidation at 1100 °C to determine their impact on coating lifetime. The results indicated that the HRR-FLR treatment was effective in reducing surface roughness, restructuring microstructures, and redistributing reactive elements. These improvements facilitated the formation of a flat, continuous, and dense alumina layer, enhancing the spallation and rumpling resistance of TGO. Consequently, the efficiency of HRR-FLR technique was proven in significantly improving the lifetime of NiCrAlY coatings, which provides a new application prospect of femtosecond lasers in remelting and polishing of metallic surfaces.