Architecting dual-phase high-entropy composite films via spinodal decomposition for enhanced resistance to wear and irradiation

• A dual-phase high-entropy composite film with a layered structure was prepared by magnetron co-sputtering. • Dual-phase high-entropy composite films exhibit superhigh hardness and excellent wear resistance. • Under the same He ion irradiation conditions, the He bubble size in the composite film is smaller than that in the metal counterpart film. • First-principles calculations indicate that doping Y 2 O 3 reduces the dissolution energy of He atoms in the system. Incorporating nanoprecipitates into alloys has emerged as a promising strategy to simultaneously enhance mechanical strength and radiation tolerance. However, the heterogeneous interfaces between precipitates and the matrix often induce localized strain fields, which may facilitate crack initiation under mechanical loading and accelerate microstructural degradation under irradiation. To overcome these limitations, we present a novel material design paradigm that combines the characteristics of spinodal decomposition with high entropy systems. In this work, Y 2 O 3 -doped AlCrFeNi composite films were prepared via magnetron co-sputtering. These films spontaneously self-assembled into a multilayered structure consisting of alternating AlCrFeNi-rich and Y 2 O 3 -rich layers. This unique microstructure leads to a remarkable enhancement in mechanical properties: the composite films possess a hardness nearly twice that of the undoped films. Tribological tests reveal a remarkable reduction in the wear rate, decreasing from 1.15 × 10 −4 mm 3 /N·m for the undoped film to 1.77 × 10 −5 mm 3 /N·m for the Y60 composite film. Furthermore, the composite films exhibit superior helium (He) ion radiation resistance, characterized by a refined distribution of smaller He bubbles after irradiation compared to the undoped sample. First-principles calculations reveal that Y 2 O 3 doping lowers the dissolution energy of He atoms in the AlCrFeNi matrix, while Y-O species serve as trapping sites that inhibit He diffusion and suppress the formation of large He bubbles. These findings offer a new route for designing materials with exceptional mechanical robustness and radiation durability.