In Situ Visualization of Electron Beam-Driven High-Entropy Alloy Crystallization.

Abstract

Achieving compositionally uniform high-entropy alloy (HEA) nanoparticles via reduction-based synthesis remains challenging due to variations in elemental reduction, diffusion, and phase stability. Using in situ transmission electron microscopy (TEM), this study visualizes the electron beam-induced crystallization of amorphous high-entropy glycerolate (HE-glycerolate) films composed of Mg, Mn, Co, Ni, and Zn. The transformation proceeds through phase separation, radiolytic reduction, and localized atomic rearrangement, producing single-phase face-centered cubic (fcc) HEA nanoparticles with uniform cuboidal morphology and dominant {100} facets. Compared to thermal annealing, the electron beam pathway offers finer control over composition and morphology by limiting atomic mobility and preventing phase segregation or Co/Ni clustering. This displacement-driven, athermal process enables gradual, diffusion-limited crystallization within confined regions, resulting in well-defined, compositionally homogeneous alloys. The study reveals the mechanism of electron beam-driven crystallization of HEA nanoparticles and establishes a broader principle that controlling atomic mobility is key to achieving stable, multielement solid solutions. The insights gained, highlighting the role of confined atomic mobility, offer a valuable foundation for designing new low-temperature synthesis routes for uniform HEA materials with controlled phase and morphology, and inform the development of scalable processing strategies for homogeneous multicomponent systems.