Reactive Synthesis and Assessment of Porous Feconicralx High-Entropy Alloys for High-Temperature Filtration

Porous FeCoNiCrAlx high-entropy alloys (HEAs) with different atomic fraction of Al were developed as potential candidates for high-temperature filter materials by reactive synthesis using blended elemental Fe/Co/Ni/Cr/Al powders. This method combines the creation of porous structure with the direct synthesis of HEAs, and takes the advantage of the role of Al in enhancing the porosity of porous materials. The effects of Al atomic fraction on the pore structure parameters, phase compositions, microstructures and mechanical strengths of porous FeCoNiCrAlx were investigated, and a comprehensive assessment of the high-temperature corrosion resistances of these materials was carried out. The results showed that the increase of Al atomic fraction not only improved the porosity and intrinsic mechanical performance of porous FeCoNiCrAlx, but also provided enhanced protection against high-temperature corrosions such as oxidation, carbonization and sulfidation. The optimal atomic fraction range of Al in porous FeCoNiCrAlx HEAs was 0.6~1.0, which could make this material keep structural and chemical stability in potential high-temperature flue gas environment.