RuAl Thin-Film Deposition by DC Magnetron Sputtering

The intermetallic transition metal B2-structured aluminide RuAl is a candidate material for use in various applications, including microelectronics and structural materials under demanding conditions, for example, as oxidation- and corrosion-resistant materials. In contrast to other B2 transition metal aluminides, which usually suffer from brittle material behavior at room temperature, RuAl exhibits comparatively good room-temperature ductility, in combination with further promising properties. Therefore, RuAl thin films are attracting interest as potential protective and functional surface engineering materials. The synthesis of RuAl thin films by physical vapor deposition, especially magnetron sputtering, is however complex and utilizes codeposition and multilayer from elemental sputtering targets and subsequent annealing procedures. Herein, an alternative route toward single-phase B2-structured RuAl thin films by nonreactive DC magnetron sputter deposition at low substrate temperature from a powdermetallurgically manufactured Ru50Al50 compound target is described. The influence of the deposition parameters on the constitution, microstructure, and selected properties of RuAl thin films is studied. It is shown that especially the Ar process gas pressure has a significant impact on their composition and morphology. X-ray diffraction and transmission electron microscopy with selected-area electron diffraction indicate that the films are single-phase RuAl with B2 structure. The synthesis and influence of deposition parameters on the corresponding microstructure of single-phase RuAl in B2 structure is examined via transmission electron microscopy analysis and X-ray diffraction with additional pole figure measurements. These are correlated to mechanical properties of the magnetron-sputtered thin films. The figure shows the strong preferential growth in (110) orientation with a fine-grained nanocolumnar v-shaped crystallite growth.image (c) 2024 WILEY-VCH GmbH