Concurrent Recrystallization and Precipitation for Combination of Superior Precipitation and Grain Boundary Hardening in Co₃₇Cr₂₀Ni₃₇Ti₃Al₃ High-Entropy Alloy

According to the precipitation and recrystallization behavior, the precipitation and recrystallization can be concurrently tuned toward the excellent mechanical property. In this study, a synergistically strengthened \({\mathrm{Co}}_{37}{\mathrm{Cr}}_{20}{\mathrm{Ni}}_{37}{\mathrm{Ti}}_{3}{\mathrm{Al}}_{3}\) high-entropy alloy was developed through concurrent recrystallization and precipitation (CRP) approach. After the treatment, the high-density γ' precipitates were introduced in the matrix, while the fully-recrystallized ultrafine grains and annealing twins were obtained from the recrystallization. Compared with conventional treatment, the CRP-HEA exhibits a superior combination of ~ 1.62GPa tensile strength and ~ 28% elongation, which is attributed to the synergistic strengthening of precipitation and grain boundary. In addition, the deformation mechanisms were characterized by TEM. The cutting-through mechanism dominates the deformation behaviors. Moreover, interesting stacking faults in different slip planes prevail during plastic deformation. The concurrent recrystallization and precipitation for ultra-fine grain structure with nano-precipitates would provide an effective strategy to achieve outstanding combination of strength and ductility.