High‐throughput additive manufacturing and characterization of CoCrFeNi–AlTi high‐entropy alloys

Abstract Co‐precipitation strengthening of the L1 2 nano‐particles along with hard intermetallic phases, including L2 1 , B2, σ and η, demonstrates significant potential for the development of advanced CoCrFeNi high‐entropy alloys (HEAs) with favorable strength‐ductility balances. Understanding the alloying effect of Al and Ti on the formation and stability of these intermetallic phases in the CoCrFeNi HEAs is crucial for efficiently exploring the multi‐component space for future alloy designs. In the present work, stepwise compositionally graded CoCrFeNi–AlTi HEAs comprising 35 different compositions were fabricated using high‐throughput additive manufacturing (AM) and analyzed through a suite of localized characterization techniques. Our analysis confirmed the existence of two primary solid solution phases, face‐centered cubic (FCC) and body‐centered cubic (BCC), as well as four distinct intermetallic phases, which include L1 2 , L2 1 , σ and η. By overlapping the zero phase fraction (ZPF) lines of these phases, the pseudo‐ternary phase diagram of the multi‐component CoCrFeNi–AlTi system at 800 °C was determined, demonstrating good agreement with the literature results. Furthermore, the composition‐dependent microstructural evolution and Vickers hardness (HV) were also established, providing numerous opportunities to design CoCrFeNi–AlTi HEAs with superior microstructure stability and balanced strength‐ductility properties for structural applications at elevated temperatures.