Insights into corrosion behavior of AlCrFeTi and AlCrFeTiMo coating in oxygen-controlled lead bismuth eutectic at 500 °C, 550 °C and 600 °C

Abstract

AlCrFeTi and AlCrFeTiMo high entropy alloy coatings were prepared on tubular F/M steel matrix by magnetron sputtering, and the corrosion behaviors of coatings after exposing to 0.5–1 × 10⁻⁶ wt% oxygen containing liquid lead bismuth eutectic (LBE) was investigated. Static LBE corrosion tests were conducted at 500 °C, 550 °C and 600 °C up to 2000 h. Both AlCrFeTi and AlCrFeTiMo coatings had experienced phase transformation from amorphous to BCC. Bi-layered oxide scales were formed on AlCrFeTi coating which consist of outer Fe₃O₄/Cr₂O₃ mixed oxides and inner Al₂O₃/TiO₂ oxides, and the inner oxide layer was strengthened with temperature raising and the amorphous features were confirmed. The addition of Mo increased the overall corrosion rate of AlCrFeTi coating, which was ascribed to the formation of MoO₃ breaking the compactness and uniformity of the inner oxide layer, and the morphology transformed from dense amorphous dominated oxide layer to segregated netlike layer.