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

A multi-dimensional Al-Co-Cr-Fe-Ni-Ti alloy space with a Ni-3(Al, Ti)-type ordered (gamma') phase in a disordered face-centered cubic matrix phase (gamma) without detrimental intermetallic phases at 800 degrees 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 gamma-gamma' structure at 800 degrees 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 at%) and (Al+Ti)-concentrations (up to 20 at%). The Ni51Co18Fe5Cr10Al12Ti4 HESA developed using the present approach exhibited a gamma'-volume fraction of 63%,.'-dissolution temperature of 1188 degrees C and showed excellent coarsening resistance and strength re-tention at 800 degrees 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. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

By integrating calculated-phase diagrams and a computational framework, a multi-dimensional alloy space with a specific ordered phase for high-temperature structural applications was obtained. The solubility limits of alloying elements at 800 degrees C were defined based on the model, and high-performance high entropy superalloys were developed.