Evaluating The Influence Of Microstructural Attributes: Fraction, Composition, Size And Spatial Distribution Of Phases On The Oxidation Behaviour Of High-Entropy Alloys

Oxidation behaviour of five high entropy alloys (HEAs): AlCoCrFeNi, Al2CoCrFeNi, Al2CoCr1.5FeNi, AlCoCrNi and AlCoCr0.5Ni, has been studied at 1100 ?C in the cast-annealed condition. Al2CoCrFeNi and AlCoCr0.5Ni HEAs exhibit the lowest oxidation rates of the order of 10-12 g2 cm-4-s- 1. Al-rich nanoscale precipitates are observed to aid protective oxide growth. The Al-lean phase fraction and its Al content also have a major effect on the alloy?s oxidation behaviour. A parameter ?X? taking the ratio of these two has been introduced, which coupled with CALPHAD predictions can be a potential tool to shortlist HEAs for oxidation resistance applications.