Microstructure and nanomechanical properties of magnetron sputtered Ti − Nb films

Titanium niobium (Ti − Nb) films, covering a broad spectrum of compositions, are deposited on silicon substrates using magnetron co-sputtering. The morphological, crystallographic and mechanical characteristics of the films are studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and nanoindentation, respectively. The Ti − Nb films exhibit a columnar growth and contain porosity at volumetric percentages of 2-14 vol%. Furthermore, it is observed that the allotropic β − Ti phase can be stabilized at room temperature for Nb compositions beyond 20 at%. Phase composition and microstructural details have subsequent implications on the mechanical properties of the films which are studied experimentally and micromechanically. Among the tested compositions, Ti85Nb15 exhibits the lowest elastic modulus. The obtained structure-property relations could serve as a tool for material optimization.