Simulation-guided design of novel precipitation-strengthened eutectic high entropy alloy

Eutectic high entropy alloys (EHEAs) with hard and ductile phases are promising for high-temperature applications. The mechanical properties of EHEAs can be improved by incorporating precipitates in the ductile phase. The study focuses on the CALPHAD-guided alloy design approach for developing EHEA with cuboidal L1₂ precipitates in the ductile phase. The newly designed alloy (Al_0.17CoCrFeNiTa_0.22) is subjected to a simulation-guided heat treatment cycle. The Al_0.17CoCrFeNiTa_0.22 alloy shows FCC phase with a needle-like Ta-rich precipitate at 12 h and Ni-Al-rich cuboidal precipitate at 24 h of heat treatment. The calculated entropy of mixing of cuboidal precipitate is higher than that of needle-like precipitate. The detailed TEM characterisation confirms the characteristics of precipitates and microstructural changes correlated with microhardness measurements. The study proposes a novel EHEA system with a nano-scale precipitation-strengthened FCC phase and eutectic colony.