Effect of stress on hot corrosion behavior of CVD aluminide coatings on Mar-M247 superalloy in the environment of humid air-Na2SO4-NaCl

Aluminide coatings were deposited on Mar-M247 alloys using the chemical vapor deposition (CVD) process. The effect of stress loading on hot corrosion behavior of Mar-M247 alloy with aluminide coating in the humid airNa2SO4-NaCl environment at 750 degrees C was investigated. The results revealed that stress induced more defects (e.g., cracks) near the scale/alloy (coating) interface and promoted the inward diffusion of corrosive media (e.g., S), which in turn accelerated the corrosion of both the alloy and coating. The scale thickness and internal corrosion penetration depth also significantly increased compared to the stress-free case. Nevertheless, the aluminide coating still effectively protected the alloy. The detrimental impact of stress on its corrosion resistance was less pronounced than that on the alloy, confirming its potential as a stress-tolerant protective system. This work provides critical insights into designing stress-resistant coatings for gas turbine components operating in aggressive environments.