High frequency eddy current method in inspection of aluminide coatings integrity after simulating service loads

• High-frequency ECT effectively detects microstructural damage in aluminide coatings. • Fine-grained substrates exhibit superior coating durability under fatigue conditions. • Thinner coatings (20 µm) show better resistance to structural degradation than 40 µm coatings. • Optimal ECT sensitivity is achieved within a narrow 11.84–12.06 MHz frequency range. • ECT enables non-destructive assessment of coating integrity for turbine maintenance. This study investigates the use of high-frequency eddy current testing (ECT) to assess the structural integrity of aluminide coatings on MAR-M247 nickel superalloy under simulated fatigue conditions. Aluminide coatings, deposited via chemical vapor deposition at thicknesses of 20 µm and 40 µm, were tested using custom-designed probes optimized for defect detection. Results demonstrate that substrate grain structure and coating thickness significantly influence coating durability, with fine-grain substrates exhibiting the least resistance changes and greatest fatigue tolerance. Eddy current signal variations correlated with microstructural changes, enabling detection of damage otherwise invisible to traditional methods. These findings establish ECT as a precise, non-destructive approach for monitoring aluminide coatings in critical applications.