Oxidation Behavior of the Y_(56)Al_(24)Co_(20) Bulk Amorphous Alloy Containing Crystalline Composites at 325-450°C

摘要

The oxidation behavior of Y_(56)Al_(24)Co_(20) bulk metallic glass containing ～4.2% Y-rich particles was studied over the temperature range of 325-450°C in dry air. The results showed that the oxidation kinetics of the alloy followed the parabolic rate law at T ≤ 375 °C, with rate constants generally increased with temperature. Conversely, para-linear kinetics were observed at higher temperatures (T ≥ 400°C). The scales formed on the Y-base amorphous composite were temperature dependent, consisting of exclusively yttrium oxides (Y_2O_3) at T ≤ 375°C and of mostly Y_2O_3 and alumina (Al_2O_3) at temperatures. No evidence of any cobalt-containing oxide was found in the scale.