Impact of Al or Si addition on properties and oxidation resistance of magnetron sputtered Zr–Hf–Al/Si–Cu metallic glasses

Abstract

Amorphous quaternary Zr–Hf–Al/Si–Cu thin-film metallic alloys were prepared by non-reactive magnetron co-sputtering using four unbalanced magnetrons equipped with Zr, Hf, Al or Si, and Cu targets. The Zr, Hf and Al or Si targets were sputtered in dc regimes while the Cu target in a high-power impulse regime. Two series of films with either Al (up to 17 at.%) or Si (up to 12 at.%) addition were deposited. The effect of the elemental composition on the structure, thermal behavior, mechanical and surface properties, electrical resistivity and oxidation resistance was systematically investigated. All Zr–Hf–Al/Si–Cu films were deposited with an X-ray amorphous structure. The glass transition was, however, recognized only up to 12 at.% Al or 6 at.% Si. The addition of Al or Si enhances mechanical properties of the films and the thermal stability of their amorphous state. This may be explained by an increase of a covalent component of the mixed metallic-covalent bonds with increasing the Al and Si content. Moreover, the Zr–Hf–Al–Cu metallic glasses exhibit a wider super-cooled liquid region, while the Zr–Hf–Si–Cu metallic glasses are more oxidation resistant.