Simultaneous Enhancement of Strength and Ductility in a CoCrFeNiAl0.5Ti0.1 Alloy via Quenching-Induced Solid-State Phase Transformation

Alloys often face a well-known trade-off: enhancing strength typically results in a reduction in ductility, and vice versa. This inherent limitation poses a significant challenge in materials engineering, particularly in applications requiring both high strength and adequate deformability. In this study, we investigate the effects of different heat treatments on the microstructures and mechanical properties of a CoCrFeNiAl0.5Ti0.1 high-entropy alloy (HEA). Our findings demonstrate that with the appropriate heat treatment, it is possible to simultaneously enhance both strength and ductility. The as-rolled CoCrFeNiAl0.5Ti0.1 HEA sheet exhibits mechanical properties with a tensile strength of 987 MPa, a yield strength of 769 MPa, and an elongation of 20.2%. After annealing treatments at 700 °C and 900 °C followed by water quenching, the alloy demonstrates simultaneous improvements in both strength and ductility. Specifically, the alloy annealed at 700 °C achieves a tensile strength of 1314 MPa, a yield strength of 970 MPa, and an elongation of 20.3%. Similarly, annealing at 900 °C results in a tensile strength of 1208 MPa, a yield strength of 727 MPa, and an elongation of 18.3%. The enhancements in mechanical properties are due to the reduction in internal stress and the occurrence of recrystallization. Additionally, the formation of fine and uniformly distributed precipitates during the heat treatment process further contributes to improvements.