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

Abstract

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. The CrNbTaVW RHEA has a higher hardness of 688 HV than the IN718 alloy with 301 HV. The higher hardness is due to Laves phase solid solution strengthening and grain refinement. From the corrosion results, CrNbTaVW RHEA had a lower corrosion rate in 3.5 wt% NaCl (0.000097 mm/yr) and 1 M H2SO4 (0.00013 mm/yr) than the commercial IN718 alloy (0.054 mm/yr and 1.12 mm/yr). The cyclic oxidation analysis at 850 °C and 1050 °C after 15 hours confirmed a mass gain of 4.41 mg/cm2 and 10.84 mg/cm2 for IN718 alloy, while CrNbTaVW RHEA exhibited a mass loss of −25.17 mg/cm2 and − 35.91 mg/cm2, respectively, indicating that the IN718 alloy exhibited the best oxidation resistance. Thermal and growth stresses contributed to the pores, voids, cracks, and spallation observed in the CrNbTaVW RHEA.