High-Entropy Alloys as Bond Coats in Thermal Barrier Coatings

Thermal barrier coatings (TBCs) are vital for boosting the performance and longevity of high-temperature components in gas turbines and jet engines, offering thermal insulation and oxidation resistance. Traditional MCrAlY bond coats, though effective, suffer from drawbacks such as rapid oxidation above ۱۱۰۰°C, substrate interdiffusion, and limited high-temperature strength. High-entropy alloys (HEAs), featuring multiple principal elements in near-equimolar proportions, present a promising alternative due to their high configurational entropy, sluggish diffusion, lattice distortion, and synergistic effects, resulting in enhanced oxidation resistance, thermal stability, and mechanical properties. This review consolidates recent progress in HEAs as bond coats, emphasizing compositions like NiCoCrAlY-based alloys, AlCrFeCoNi, and refractory variants applied via thermal spray methods such as high-velocity oxy-fuel (HVOF), atmospheric plasma spray (APS), and high-velocity air-fuel (HVAF). Notable outcomes include improved oxidation resistance via stable alumina scales, reduced interdiffusion, and extended TBC durability under thermal cycling. Issues like in-flight oxidation and phase changes are explored, alongside future strategies for optimizing HEA compositions with reactive elements such as Y and Hf. This study underscores HEAs' potential to push TBC operating temperatures beyond current thresholds, benefiting aerospace and power generation sectors.

کلیدواژه ها:

HEA ، TBC ، Bond Coats ، Oxidation Resistance ، Thermal Spray