Effect of Al, Zr and Mo on corrosion resistance of Al_xCrFeNiMo and Al_xCrFeNiZr (X = 1, 1.2 and 1.4) as nuclear fuel cladding materials

The high entropy alloy of Al_xCrFeNiM (with x = 1, 1,2 and 1,4; M = Mo and Zr) was successfully synthesized using powder metallurgy technique with sintering process at 1000 °C in an inert atmosphere. These alloys were designated as fuel cladding for research reactor with high U-density fuel such as U-Mo. One of the critical in-service properties of nuclear fuel cladding is its corrosion behavior. In this study, some properties of the HEA of Al_xCrFeNiM such as the phases, microstructures, hardness, and corrosion resistance in 3 wt.% NaCl solution at room temperature were investigated. The results show that the phases in the HEA of Al_xCrFeNiMo are FeNi, AlNi and Mo. The HEA of Al_xCrFeNiZr has more complex phases compared to the Al_xCrFeNiMo. The microstructure of HEA samples show fine grains with some micropores that imperfect the solidification during the sintering process. The hardness value of the HEA of Al_xCrFeNiMo has a trend of decreasing as the x value increases. The opposite trend occurs to the HEA of Al_xCrFeNiZr that the hardness value increases with increasing x value. The lowest hardness value is Al_1.4CrFeNiMo at 262.2 HV, and the highest hardness value of Al_1.4CrFeNiZr is at 756.7 HV. The corrosion rate of the Al_xCrFeNiMo does not show a specific trend with increasing x value; however, the Al_xCrFeNiZr shows decreasing value with increasing x value. The lowest value for the all-HEA samples is 0.20 mpy for the Al_1.4CrFeNiZr. The results of hardness and corrosion tests show that the Zr element combined with the Al element affects not only its hardness but also its corrosion resistance. (author)