| Abstract Scope |
Self-organization during growth of elevated temperature sputter co-deposition of alloy thin films with immiscible elements could lead to monomodal or hierarchical phase-separated morphologies. Using transmission electron microscopy characterization of a series of immiscible alloy systems, (Cu-Mo, Cu-Ag, Cu-Fe, Cu-Ta, Mo-Ag, Cu-Mo-Ag), and phase-field modeling, indicate that hierarchical structures form with sufficient disparity in kinetic energy between the constituent atoms, one species being highly mobile (A) and the other relatively immobile (B). Typically, reduced deposition rate and large difference in homologous temperatures of the depositing elements tends to favor the formation of hierarchical morphology comprised of multiple phase-separated microstructure morphologies from nanometer to sub-micrometer scales. The observations are interpreted via a model incorporating material properties and process parameters. Thin films with hierarchical morphologies exhibit high flow strengths that are comparable to monomodal nanoscale morphology but significantly higher strain hardening rate, higher plastic deformability and higher fracture resistance. |