Microstructures in arc-welded Al10Co25Cr8Fe15Ni36Ti6 and Al10.87Co21.74Cr21.74Cu2.17Fe21.74Ni21.74 multi-principal element alloys: Comparison between experimental data and thermodynamic predictions

The development of multi-principal element alloys is currently on the rise. While there is significant fundamental work being performed to understand microstructure-property relationships, the processability of these novel alloys is yet incipient. In this work, the microstructure evolution in two arc-welded multi-principal element alloys, Al10Co25Cr8Fe15Ni36Ti6 and Al10.87Co21.74Cr21.74Cu2.17Fe21.74Ni21.74, was evaluated by electron micro-scopy and high energy synchrotron X-ray diffraction coupled with thermodynamic calculations. By correlating microhardness maps across the welds to results from microstructure characterization, it was possible to identify the strengthening phases across the welded materials, which can aid in fine tuning the alloy microstructure to achieve targeted strengths. Moreover, a comparison between the thermodynamically predicted microstructure evolution and that present in the welded joints was performed, highlighting the difficulty of such predictions in complex, scarcely studied multi-principal element systems.