The AlCrFe2Ni2 HEA possesses two dominant crystallographic arrangements in its microstructure: BCC and FCC. Each arrangement has configurationally ordered and disordered variants, totaling at four available phases as function of production parameter, and heat treatments.
In this work, three thermal states of the alloy were obtained: as-cast, homogenized, and homogenized and aged. Microstructural analysis was performed by HRSEM, EBSD, TEM and HRTEM. Tensile properties of all three states were determined using in-situ tension tests.
The ultimate tensile strength of all states hovered in the 1200-1300MPa range. Plastic deformation in as-cast and homogenized states concentrated solely in the FCC phase, exhibiting characteristic dislocation slip lines. The BCC domains impeded dislocation movement by forcing the active slip systems to alternate until a continuous path was completed. The ductility of the aged alloy decreased due to the formation of very fine L12 precipitates, which eliminated free dislocation movement in the FCC phase altogether.