Effect of initial grain structure on the concurrent precipitation and recrystallization of Co₃₇Cr₂₀Ni₃₇Ti₃Al₃ high-entropy alloy

High performance precipitation strengthened high-entropy alloys (HEAs) can be prepared by concurrent recrystallization and precipitation in the process of aging at intermediate temperatures after rolling. Generally, the homogenized samples are subjected to rolling before aging, where the effects of initial grain structure before rolling on the concurrent recrystallization and precipitation are overlooked. In this study, we revealed the inherited effect of initial grain on the concurrent recrystallization and precipitation in Co₃₇Cr₂₀Ni₃₇Ti₃Al₃ HEA. The heredity of grain homogeneity to the initial grain structure was revealed, where the initial grain structure influences the homogeneity of strain distribution during rolling and influences the recrystallization in the subsequent aging. Moreover, the inherited effect of the initial grain structure also influences the precipitation behavior. TEM characterization confirmed that the lamellar precipitation decreases, while spherical precipitation increases with the increase of the initial grain size. By tailoring the initial grain size, the strength and ductility of Co₃₇Cr₂₀Ni₃₇Ti₃Al₃ alloy were simultaneously improved. The present study provides a good understanding of the concurrent recrystallization and precipitation in HEAs.