The oxidation behavior of the CrFeCoNiAlx (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 degrees C. Al forms the Al2O3 under the top Cr2O3 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 Al2O3 formations were observed for the sample with the highest aluminium concentration due to dissolution of nitrogen in the as-built material.

Automated summary

By evaluating the oxidation resistance of high-entropy alloys (HEAs) at different temperatures, it is found that the formation of Al2O3 layer in HEAs can prevent the delamination of the oxide scale and enhance the oxidation resistance. The addition of Al element leads to the formation of AlN, further improving the oxidation resistance of the material.