The oxidation behavior of the CrFeCoNiAl (x = 0, 1.0, and 5.0 wt%) high-entropy alloy synthesized with Al elemental powder via powder bed fusion technique at high temperatures.

High-entropy alloys (HEAs) are promoted as promising materials for various applications, including those dealing with high-temperatures. It requires understanding of the oxidation at different temperatures, especially for such a technological process as additive manufacturing (AM), which is able to produce unique structure. The present work evaluates the oxidation resistance of the CrFeCoNiAl HEAs produced by AM of the blends of CrFeCoNi and Al powders at temperatures of 800 and 1000 ℃. Al forms the AlO under the top CrO layer and prevents the delamination of the oxide scale at considered temperatures. Oxygen diffusion mainly occurs homogeneously through the columnar grain boundaries typical for AM materials. AlN precipitates under the AlO formations were observed for the sample with the highest aluminium concentration due to dissolution of nitrogen in the as-built material.