Computational design of thermally stable and precipitation-hardened Al-Co-Cr-Fe-Ni-Ti high entropy alloys

Abstract

Abstract A multi-dimensional Al-Co-Cr-Fe-Ni-Ti alloy space with a Ni3(Al, Ti)-type ordered (γ’) phase in a disordered face‐centered\xa0cubic matrix phase (γ) without detrimental intermetallic phases at 800\xa0°C was obtained by integrating calculated-phase diagrams and a computational framework. The solubility limits of alloying elements in the compositional space were defined for the γ-γ’ structure at 800\xa0°C. The present model was calibrated with high entropy superalloys (HESAs) from the literature and experimentally validated by the synthesis of HESAs with an extended range of Al (10.5–15\xa0at%) and (Al+Ti)-concentrations (up to 20\xa0at%). The Ni51Co18Fe5Cr10Al12Ti4 HESA developed using the present approach exhibited a γ’-volume fraction of 63%, γ’-dissolution temperature of 1188\xa0°C and showed excellent coarsening resistance and strength retention at 800\xa0°C. The current approach aids the high-throughput design of potential high-performance Al-Co-Cr-Fe-Ni-Ti HESAs for high-temperature structural applications without the need for expensive alloying elements.