High-throughput characterization of early oxidation across AlxFeyNi1−x−y composition space

•Thin-film combinatorial libraries can contain every AlFeNi alloy composition.•We have studied oxidation of full-range AlFeNi libraries in dry air at 427 °C.•High-throughput methods were developed to characterize oxidation behaviour.•Four phenomenologically distinct regions are identified across AlFeNi space.•The continuous boundary of internal/external oxidation transition is identified.

Improving our fundamental understanding of the oxidation of multicomponent alumina-forming alloys is crucial to their ongoing development. In this work, high-throughput methods were developed to study oxidation of AlxFeyNi1−x−y alloys in dry air at 427 °C using composition spread alloy films as combinatorial libraries (x = 0 → 1, y = 0 → [1−x]). The results divide the AlxFeyNi1−x−y   composition space into four regions of phenomenologically distinct oxidation behaviour. The boundary defining the critical Al concentration, NAl∗ (x, y), for establishment of a passivating Al2O3 scale was determined across the entire continuous AlxFeyNi1−x−y composition space.