Enhancing mechanical properties of dual-phase Al0.5CoCrFeNiSi0.25 high entropy alloy via thermomechanical treatment

Developing structural materials that possess both high strength and high ductility is a classic challenge in the design of alloys. Here, we use thermomechanical treatment to improve the strength and ductility of the Al0.5CoCrFeNiSi0.25 dual-phase high entropy alloy (DHEA). The homogenized DHEAs are cold-rolled at 40 % and then annealed at 1100 degrees c for 1 h, 5 h, and 10 h. The effects of annealing time on microstructure and mechanical properties are investigated. The results show that the microstructure of the alloy consisted of FCC/BCC dual-phase phase. The microstructure morphologies become from the fine-lamellar structure of as-cast alloy to the coarse-lamellar structure of the homogenized alloy. After thermomechanical treatment, a large number of Sigma 3 twin boundaries appeared in the FCC phase, and B2 phase particles are dispersed in the BCC phase. The average grain size remain at the sub-micron level. In addition, annealing time has little effect on the phase proportion of the alloy after 1 h treatment. The homogenized Al0.5CoCrFeNiSi0.25 DHEA annealed for 1 h at 1100 degrees c after cold rolling overcomes the strength-ductility trade-off, with high tensile strength of is 1267.8 MPa, and an excellent elongation to fracture of 34.4 %. With the increase of annealing time, the tensile strength of the alloy decreases, and the ductility appears to increase firstly then decrease. (C) 2022 Elsevier B.V. All rights reserved.