Microstructural characterization and mechanical properties of an Al0.5CoCrFeCuNi high-entropy alloy in as-cast and heat-treated/quenched conditions

The crystal structures, microstructural evolution and mechanical properties of as-cast and heat-treated/quenched Al0.5CoCrFeCuNi high-entropy alloy are investigated. The as-cast alloy exhibits a structure of (Co, Cr, Fe)-rich FCC1 dendrite and Cu-rich FCC2 interdendrite without the formation of ordered intermetallic compounds. The parameters representing simple solid-solution formation ability in multi-component alloy systems are estimated. The AlNi-rich BCC phase and AlCu-rich nanophases precipitate during annealing up to 800 °C. Age hardening and improved compressive properties are achieved after the alloy is heat-treated/quenched at 600 °C for 24 h. However, age softening and strength drop occur in case of annealing at 1000 °C as the BCC phase and nanoprecipitates are dissolved into the coarsening matrix.