A NOVEL 3d TRANSITION-METAL ALCOCRCUTI HIGH-ENTROPY ALLOY

The phase component, microstructure and compressive properties of a novel 3d transition metal high entropy alloy, AlCoCrCuTi, in as-cast and annealed conditions were investigated. The phases of the as-cast AlCoCrCuTi alloy are composed of primary phase AlCo2Ti (L21), eutectic structure {AlCo2Ti (L21)+ Al3Cr7 (BCC)} and interdendritic phase AlCu2Ti (L21). Through annealing, a rosette feature of the as-cast AlCo2Ti + Al3Cr7 eutectic structure is deteriorated due to the lath-like Al3Cr7 changed to finely-divided one. In mechanics performance, the as-cast alloy exhibits a balanced synergy in hardness (593±37 HV) and ultimate strength (745 MPa), while the hardness of the annealed alloy slightly increases to 647±23 HV at the expense of the ultimate strength. Moreover, the alloy either in as-cast or annealed conditions unfortunately display a typically brittle character. The deficiency of elongation might stem from the diversified brittle and hard phases incorporated, such as AlCo2Ti + Al3Cr7.