image: (a) Overview of the designed process chain, including cold rolling deformation, recrystallization, and single-crystallization annealing. (b) Universal framework for the fabrication of single-crystal Cu foils. Shown are the evolution of dislocation density (ρ) during cold rolling and cube texture area fraction (fc) after recrystallization annealing as a function of true strain (ε).
Credit: ©Science China Press
Copper (Cu) foil, with its exceptional electrical and thermal conductivity, serves as a foundational material for integrated circuits, high-frequency communication, and advanced energy technologies. However, commercial Cu foils are typically polycrystalline, where the abundance of grain boundaries induces severe electron scattering, thermal degradation, and interfacial instability, thereby limiting device performance and reliability. In contrast, single-crystal Cu foil possesses a highly ordered, grain-boundary-free lattice that enables the fundamental elimination of these intrinsic limitations, establishing it as a critical material for next-generation high-performance electronic systems. Although recent advances have enabled the production of single-crystal Cu foils using commercial rolled precursors, the inherent variability in texture type and intensity among these sources leads to pronounced structural heterogeneity, significantly impeding process controllability and scalable fabrication.
Recently, Prof. Enge Wang (Chairman of Songshan Lake Materials Laboratory), together with Prof. Muhong Wu and Prof. Ying Fu (Songshan Lake Materials Laboratory), Associate Prof. Zhibin Zhang (Peking University), and their collaborators, demonstrated a universal texture-controlled approach for the scalable fabrication of large-scale single-crystal metal foils. Their findings, published in National Science Review in a paper titled “Texture-controlled growth of large-scale single-crystal metal foils”, unveiled the intrinsic mechanism of single-crystal growth in metal foils and established a general strain–energy–texture framework with broad universality.
Central to the strategy is a three‑stage processing route. First, tailored cold rolling introduces a high density of dislocations, accumulating sufficient stored energy. Second, controlled low-temperature recrystallization releases the stored energy and promotes the development of a uniform {100} cube texture in the recrystallized microstructure. Third, high‑temperature annealing leverages energy‑modulation (surface and interface energies) to drive a stable transition from a cube‑textured polycrystal to a single crystal. By quantitatively correlating true strain with dislocation density and cube texture fraction, the authors identify an optimal deformation window (true strain of 4.5–5.0), in which the cube texture fraction exceeds 90% and single‑crystal growth becomes reliably achievable.
Using this approach, the team successfully fabricated large-scale single-crystal Cu foils, including a Cu(111) foil with dimensions of 33 × 20 cm2 and foils with six distinct high-index orientations. The universality of the framework was further demonstrated across multiple Cu precursor systems—including cast, rolled, and electrodeposited—and extended to nickel. These results highlight the broad applicability and significant industrial potential of the proposed method. This study not only provides a novel research paradigm for the fabrication of single-crystal metals but also establishes a critical technological foundation for the industrial application of single-crystal metal foils.
Journal
National Science Review