On crystallization and oxidation behavior of Zr54Cu46 and Zr27Hf27Cu46 thin-film metallic glasses compared to a crystalline Zr54Cu46 thin-film alloy

Amorphous Zr54Cu46 and Zr27Hf27Cu46 thin-film metallic glasses were prepared by non-reactive magnetron co-sputtering of Zr, Hf and Cu in pure argon. Several as-deposited Zr54Cu46 films were post-annealed in high vacuum to create a crystalline thin-film alloy of the identical composition. The non-isothermal crystallization behavior of the amorphous Zr54Cu46 and Zr27Hf27Cu46 films and the effect of a substitution of Hf for Zr on the crystallization process were studied by differential scanning calorimetry. The activation energy of the crystallization was obtained by the Kissinger-Akahira-Sunose method. The results show that the activation energy of the Zr27Hf27Cu46 film was higher for all conversion fractions, which indicates that the substitution of Hf for Zr enhances the thermal stability of the glassy state. Considerable attention was also paid to the isothermal oxidation behavior of the amorphous and crystalline Zr54Cu46, and amorphous Zr27Hf27Cu46 films investigated by thermogravimetric analysis. It was shown that all oxidation curves in the temperature range from 400 to 575 °C obeyed the parabolic law. The activation energy of the oxidation process determined by the Arrhenius equation for the oxidation rate constants was found to be the highest for the Zr27Hf27Cu46 film, which indicates that its surface oxide layer is a more effective barrier against the diffusion of species.