Examination of the Oxidation and Metal–Oxide Layer Interface of a Cr–Nb–Ta–V–W High Entropy Alloy at Elevated Temperatures

The authors report on the evaluation of oxide scale and interface microstructure a Cr–Nb–Ta–V–W refractory high entropy alloy (HEA) at elevated temperatures. HEA is oxidized 700 800 °C in lab air substrate/oxide investigated. Combined situ X-ray diffraction (XRD) coupled with ex scanning electron microscopy (SEM) energy dispersive spectrometry (EDS) analyses characterize confirm phases present substrate which have been previously identified this alloy. near studied for an indication selective oxidation Cracking porosity are found along layer grows directionally outward. Two main oxides identified: W-based needle-like structure Cr containing Ta that has granular structure, primarily clusters. layers porous, no dense protective identified. It when temperature increased to °C, exhibits increase thickness. In XRD indicates V first element oxidize.