Effect of Sc on the Water Vapor Oxidation Behavior of FeCrAl Alloys at 1000 °C

This study analyzes the oxidation behavior of FeCrAl–(0.0, 0.5, 1.0, 2.0, and 4.0) wt% Sc alloys prepared through vacuum hot‐press sintering in a water vapor environment. Sc diffuses via short‐circuit diffusion from the oxide scale/alloy interface to the oxide scale surface. Subsequently, Sc is segregated at the aluminum oxide scale interface, preventing Al ions from diffusing outward to combine with the oxygen in the water vapor and reducing the growth rate of the oxide scale. Compared to a pure oxygen atmosphere, the water vapor atmosphere affects the adhesion of the oxide scale, shedding the oxide scale and leading to secondary oxidation. Sc doping transforms the oxide scale from a state of easily curved, poorly bonded, and full voids into a flat, bonded, dense, and protective scale. A dopant content of 0.5 wt% Sc is low and has a minor effect on the oxidation resistance of FeCrAl alloys. Samples containing 2.0 and 4.0 wt% Sc are excessively doped, causing considerable internal oxidation. In this experiment, 1.0 wt% Sc doping is found to be the most appropriate, demonstrating a low mass gain of 2.59 ± 0.12 mg cm⁻² and a slow oxidation rate (K _p = 0.7131 mg cm⁻² · h ⁿ ).