Atomistic insights into continuous and discontinuous precipitation in high-entropy alloys: Role of interfacial and elastic anisotropy

• Anisotropy in interfacial and strain energies is identified as the primary factor governing precipitate morphology, with Cr and Ti as the most influential elements. • Ti exhibits a strong affinity for Ni, resulting in an unstable precipitate/matrix interface, whereas Cr induces unusual magnetic reversals at the interface. • Ti enhances elastic anisotropy by raising both lattice and elastic misfit, while Cr primarily increases elastic anisotropy through increased elastic misfit. An atomic-scale understanding of precipitation mechanisms is essential for elucidating and ultimately controlling the microstructure and properties of precipitation-strengthened high-entropy alloys (HEAs). In this study, we investigate the fundamental mechanisms governing the precipitation mode and microstructure evolution in Fe–Co–Ni–Cr–Ti–Al-based FCC/L1 2 HEAs by integrating first-principles calculations with experimental validation. Comprehensive evaluation of parameters associated with precipitation morphologies identifies anisotropy in interfacial and strain energies as the primary factors controlling precipitate morphology, with Cr and Ti emerging as the most influential elements that affect energy anisotropy in the alloys. From the perspective of interfacial energy anisotropy, Ti demonstrates a strong affinity for Ni, resulting in an unstable FCC–Ni/L1 2 –Ni 3 Ti interface, whereas Cr induces unusual magnetic reversals at the FCC/L1 2 interface, thereby increasing interfacial energy anisotropy. Regarding strain energy anisotropy, increasing Ti content enhances anisotropy by increasing both lattice and elastic misfit, while increasing Cr content amplifies elastic anisotropy primarily through enhanced elastic misfit. The theoretical predictions were validated by a series of alloy experiments. These findings offer new insights into precipitation mechanisms and provide valuable guidelines for the future design of alloys with tailored microstructures.