Impurities can be incorporated during thin film deposition, but also can originate from atmosphere exposure. As impurities can strongly affect the composition—structure—property relations in magnetron sputter deposited thin films, it is important to distinguish between both incorporation channels. Therefore, the impurity incorporation by atmosphere exposure into sputtered Mg, Al, and Ca thin films is systematically studied by a variation of the deposition temperatures and atmosphere exposure times. Deposition temperature variation results in morphological modifications explained by considering surface and bulk diffusion as well as grain boundary motion and evaporation. The film morphologies exhibiting the lowest oxygen concentrations, as measured by energy dispersive X-ray spectroscopy, are obtained at a homologous temperature of 0.4 for both Mg and Al thin films. For Ca, preventing atmosphere exposure is essential to hinder impurity incorporation: By comparing the impurity concentration in Al-capped and uncapped thin films, it is demonstrated that Ca thin films are locally protected by Al-capping, while Mg (and Al) form native passivation layers. Furthermore, it can be learned that the capping (or self-passivation) efficiency in terms of hindering further oxidation of the films in atmosphere is strongly dependent on the underlying morphology, which in turn is defined by the growth temperature.

We report on the formation of Ag-containing ZrCuAlNi thin film metallic glass (nano)composites by a hybrid direct-current magnetron sputtering and high-power pulsed magnetron sputtering process. The effects of Ag content, substrate temperature and substrate bias potential on the phase formation and morphology of the nanocomposites were investigated. While applying a substrate bias potential did not strongly affect the morphological evolution of the films, the Ag content dictated the size and distribution of Ag surface segregations. The films deposited at low temperatures were characterized by strong surface segregations, formed by coalescence and Ostwald ripening, while the volume of the films remained featureless. At higher deposition temperature, elongated Ag segregations were observed in the bulk and a continuous Ag layer was formed at the surface as a result of thermally enhanced surface diffusion. While microstructural observations have allowed identifying both surface and bulk segregations, an indirect method for detecting the presence of Ag segregations is proposed, by measuring the electrical resistivity of the films.

The formation of surface films and local alkalization during the aqueous corrosion of Mg alloys significantly influences their corrosion properties across various electrolytes. This study provides new insights into the layer formation on a Mg-1.06Al-0.046Ca alloy immersed in an alkaline electrolyte (pH = 11.5) for 72 h, utilizing (electro-)chemical analysis. This study contributes new evidence supporting the formation of a subsurface Al-enriched interlayer (~4 at.%) in a Mg–Al–Ca alloy under alkaline conditions. Atom probe tomography and scanning transmission electron microscopy show the absence of Ca segregation at the metal and corrosion product interface. The corrosion product itself is a three-layer structure: next to the substrate a Mg(OH)2_dense layer, followed by an Al-enriched interlayer 2, and an outer Mg(OH)2_flake layer. Changes in diffusion-related transport properties are observed after 20.5 h of immersion, as indicated by the impedance response associated with the Mg(OH)2_dense layer and the subsurface Al interlayer 1.