High-throughput characterization of the effects of H2O vapour on early oxidation across AlxFeyNi1 − x − y composition space

The presence of H2O vapour in an oxidizing environment can increase the critical aluminium concentration, NAl*, required to establish a passivating Al2O3 scale in multicomponent alumina-forming alloys. This work used AlxFeyNi1 − x − y composition spread alloy film combinatorial libraries to determine NAl*(x, y) continuously across AlxFeyNi1 − x − y composition space (x = 0 → 1, y = 0 → [1 − x]) in a 10% H2O/air mixture at 427 °C. The NAl*(x, y) in this environment was significantly higher across much of composition space than that previously measured in dry air. Physical insights from the observed differences are considered using a modified Wagner-Maak model.