Effects of the B2 phase on the corrosion behavior of Fe-Ni-Cr-Al medium-entropy alloys in lead-bismuth eutectic

The inherent lattice distortion and slow diffusion effects of medium-entropy alloy (MEAs) can decrease element dissolution and promote the formation of a uniform oxide scale, making HEAs promising candidates for cladding materials in Generation IV fast-spectrum nuclear reactors. This study utilizes heat treatments at various aging temperatures to control the types (B2 or L12) and volume fractions of precipitates in Fe50Ni25Cr15Al10 MEAs. The corrosion behavior of these MEAs are investigated when exposed to liquid lead-bismuth eutectic (LBE) at 550 degrees C for 1000 h with a dissolved oxygen concentration of 1.93 x 10-7wt%. As the aging temperature increases, the volume fraction of the B2 phase in the MEA rises from 15.3 % to 23.9 %, which facilitates the development of a protective and dense Cr2O3 and Al2O3 double-layer oxide scale on the MEA surface. The dense double-layer oxide scale effectively prevents the formation of porous Fe3O4 on the MEA surface, thereby significantly enhancing the LBE corrosion resistance of the FCC/B2 structural MEA.