Microstructure, hardness, oxidation and corrosion behavior of Cr(VNb)2 Laves containing CrNbTaVW RHEA in 3.5 wt% NaCl and 1 M H2SO4

In this study, CrNbTaVW RHEA was produced via vacuum arc melting. The microstructure, hardness, corrosion and oxidation properties were explored in comparison with the commercial IN718 alloy. The results indicated that CrNbTaVW RHEA exhibited a dendritic microstructure that was segregated into BCC1, BCC2, and Cr(VNb)2 Laves. CrNbTaVW has a higher hardness of 688 HV in comparison with IN718 with 301 HV. Higher hardness was due to Laves phase solid solution strengthening and grain refinement. From the corrosion results, CrNbTaVW RHEA has a lower corrosion rate in 3.5 wt% NaCl (0.000097 mm/yr) and 1 M H2SO4 (0.00013 mm/yr) when compared to commercial IN718 alloy (0.054 mm/yr and 1.12 mm/yr). The cyclic oxidation analysis at 850 °C and 1050 °C for 15 h confirmed a lower mass gain of 4.41 mg/cm2 and 10.84 mg/cm2 for IN718 alloy, while CrNbTaVW RHEA exhibited mass loss of −25.17 mg/cm2 and − 35.91 mg/cm2 indicating that IN718 alloy exhibited the best oxidation resistance. Thermal stress and growth stress contributed to pores, voids, cracks, and spallation that led to the ingress of oxygen into the metallic substrate and hence mass loss for CrNbTaVW RHEA.