Combinatorial Study of Gradient Ag–Al Thin Films: Microstructure, Phase Formation, Mechanical and Electrical Properties

A combinatorial approach is applied to rapidly deposit and screen Ag–Al thin films to evaluate the mechanical, tribological, and electrical properties as a function of chemical composition. Ag–Al thin films with large continuous composition gradients (6–60 atom % Al) were deposited by a custom-designed combinatorial magnetron sputtering system. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and four-point electrical resistance screening were employed to characterize the chemical composition, structure, and physical properties of the films in a time-efficient way. For low Al contents (<13 atom %), a highly (111)-textured fcc phase was formed. At higher Al contents, a (002)-textured hcp solid solution phase was formed followed by a fcc phase in the most Al-rich regions. No indication of a μ phase was observed. The Ag–Al films with fcc-Ag matrix is prone to adhesive mate...