Oxidation Behavior of CuZr-Based Glassy Alloys at 400 °C to 500 °C in Dry Air

Abstract

The oxidation behavior of the Cu 47.5 Zr 47.5 Al 5 (Cu3) and Cu 47 Ti 34 Zr 11 Ni 8 (Cu4) bulk metallic glasses (BMGs) was studied over the temperature range of 400°C to 500°C in dry air. The oxidation kinetics of both alloys generally followed a multistage parabolic-rate law, and the steady-state parabolic-rate constants (k p values) fluctuated with temperature for the Cu3 BMG, but increased with increasing temperature for the Cu4 BMG. The scales formed on the BMGs were strongly dependent on the temperature and alloy composition, and were composed primarily of tetragonal-ZrO 2 (t-ZrO 2 ) and minor amounts of Al 2 O 3 , Cu 2 O, and CuO at 400°C for the Cu3 BMG, while the monoclinic-ZrO 2 (m-ZrO 2 ) phase is present at T ‡ 425°C, and the Cu 2 O phase is absent at 500°C. Conversely, the scales formed on the Cu4 BMG consisted exclusively of CuO at 400°C, while minor amounts of t-ZrO 2 , TiO 2 , and ZrTiO 4 formed at 425°C to 450°C, and TiO was also detected at higher temperatures. It was found that both amorphous Cu3 and Cu4 substrates transformed into different crystalline phases, and were strongly dependent on temperature and duration of time.

Air‐Oxidation of a Cu45Zr45Al5Ag5 Bulk Metallic Glass

“…The CZA4-BMG was prepared by an injection-casting technique, described elsewhere [11] . The average composition in atomic percent for the CZA4-BMG, analyzed by X-ray wavelength-dispersive spectroscopy (WDS), contained 45.03% Cu, 45.10% Zr, and 4.94% Al, and 4.93% Ag.…”

“…It is interesting to note that the k p values of the CZA4-BMG progressively increase with the temperature when it is below 450 8C, while a significant lower k p value is obtained at 500 8C, which corresponds to a slower scaling rate. For comparative purposes, the k p values of the CZA3-BMG obtained previously [11] are also summarized in the same table. Obviously, the steady-state k p values of the CZA4-BMG are slightly lower than those of the CZA3-BMG at T 425 8C.…”

“…However, little work has been done on the oxidation behavior of the CZA4-BMG with the Ag addition although that of the Ag-free alloy (CZA3-BMG) has been studied previously. [11] Thus, the main goal of this work is to investigate the oxidation behavior of the CZA4-BMG, and, in particular, to understand the role of Ag on the oxidation kinetics with respect to those of the CZA3-BMG. …”

The oxidation behavior of Cu42Zr42Al8Ag8 bulk metallic glasses

“…Minor amounts of m-ZrO 2 were observed at high temperatures (420-460°C) but absent at low temperatures (330-390°C). The formation of m-ZrO 2 was commonly seen in the high-temperature (above T g ) oxidation of Zr-based metallic glass [18,19]. The structures of substrates were also examined.…”

Oxidation Behavior of Zr43Cu45Al12 Bulk Metallic Glass at 400-525 °C in Air Atmosphere

“…Oxidation behavior of Zr-based metallic glasses has been examined by several authors . Especially interesting results have been obtained for the Zr-CuAl ternary alloys (Ref [16][17][18] in which the inversion of oxidation kinetics is observed, as well as strong dependence of the scale composition on the temperature. Kai et al (Ref 17,18) reported a non-intuitive dependence of Al 2 O 3 formation process on the concentration of Al in the alloy.…”