The oxidation behavior of Cu–Zr–Ti–base bulk metallic glasses in air at 350–500 °C

Abstract

The oxidation behavior of two Cu-base bulk metallic glasses (BMGs), having compositions Cu-30Zr-10Ti and Cu-20Zr-10Ti-10Hf (in at.%), was studied over the temperature range of 350-500°C in dry air. In general, the oxidation kinetics of both BMGs followed the parabolic rate law, with the oxidation rates increasing with increasing temperature. The addition of Hf slightly reduced the oxidation rates at 350-400°C, while the opposite results observed at higher temperatures. It was found that the oxidation rates of both BMGs were significantly higher than those of polycrystalline pure-Cu. The scales formed on both BMG alloys were strongly composition dependent, consisting of mostly CuO/Cu 2 O and minor amounts of cubic-ZrO 2 and ZrTiO 4 for the ternary BMG, and of CuO, cubic-ZrO 2 , and Zr 5 Ti 7 O 24 for the quaternary BMG. The formation of ternary oxides (ZrTiO 4 and Zr 5 Ti 7 O 24 ) was inferred to be responsible for the fast oxidation rates of the BMGs.

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

“…Thus, the additions of 31 pct Ti and 11 pct Zr into the amorphous alloy should provide higher probability to form TiO 2 , ZrO 2 , or ZrTiO 4 in the scales, as shown in Figures 7 and 9. However, as also indicated in previous a study, [17] the formation of cubicZrO 2 and ZrTiO 4 or Zr 5 Ti 7 O 24 in the oxidation of Cu 60 Zr3 0 Ti 10 and Zr 60 Zr 20 Hf 10 Ti 10 BMGs resulted in faster oxidation rates as compared to those of pure Cu. Thus, one may conclude that the slower oxidation rates obtained in the Cu4 BMG are mainly contributed by formation of TiO 2 or by a synergistic effect of combining TiO 2 with ZrTiO 4 .…”

Bulk metallic glassy surface native oxide: Its atomic structure, growth rate and electrical properties

“…Thermal oxidation of ZrACu-based BMGs was found to follow one of two mechanisms [31]: either nodules of tetragonal ZrO 2 with embedded nanocrystals of other late transition metals (CuO and ZrO 2 oxides on the surface of Zr 55 Cu 30 Al 10 Ni 5 BMG [32] or Cu 2 O, CuO and tetragonal ZrO 2 on CuAZrAAl BMG [33]); or formation of a lamellar structure of the tetragonal and monoclinic forms of ZrO 2 (Cu 50 Zr 50 and Cu 46 Zr 46 Al 8 metallic glasses [34]). On the other hand layers of CuO/Cu 2 O and a minor fraction of cubic-ZrO 2 were formed on Cu-rich Cu 60 Zr 30 Ti 10 metallic glassy surface [35]. ZrAPd BMG forms two polymorphs of crystalline ZrO 2 at different temperature ranges [36].…”

Oxidation behavior of the (Cu78Y22)98Al2 bulk metallic glass containing Cu5Y-particle composite at 400–600°C

“…The possible answer to the first formation of copper oxides is that Cu had a much higher activity than Y and Al when the nano-composite was exposed to the air, which gave it a high probability to react with oxygen to form copper oxides (Cu 2 O, CuO, or both). Yet, an addition of 2% Al into the nano-composite may significantly change the growth of the two copper oxides under the multiphase effect, in which the scaling rate of CuO could be much faster than that of Cu 2 O [18,19]. As a result, no Cu 2 O was obtained on CYA-composite after air oxidation at 400e600 C.…”