Influence of the microstructure on the short-term oxidation behavior of the AlCrCoFeNi 2.1 eutectic multi-principal element alloy

Multi-principal element alloys are considered a promising option for high-temperature applications due to their potential for excellent oxidation resistance. However, processing conditions play a crucial role in determining the final microstructure and, consequently, the material's properties. This study examines the impact of the microstructure on the mechanical properties and high-temperature oxidation behavior of a non-equiatomic AlCrCoFeNi_2.1 eutectic multi-principal element alloy. The alloy was fabricated using traditional arc melting and a powder metallurgy (PM) technique, specifically, spark plasma sintering (SPS). While the fabrication method had a minimal effect on the primary phases present, it significantly impacted the microstructure morphology. All the samples consisted primarily of a mixture of body-centered cubic and face-centered cubic phases. However, the arc-melted alloy exhibited a typical lamellar structure, whereas the SPS samples displayed globular structures in certain regions. Using a PM method significantly refined the grain size. PM routes enabled the microstructure of the samples to be tailored to improve mechanical properties and oxidation resistance. During oxidation tests, the samples fabricated using PM exhibited more homogeneous oxide layers.