Cu47Ti34Zr11Ni8塊狀非晶在375~500℃空氣之氧化

Oxidation Behavior of Cu47Ti34Zr11Ni8 Bulk Metallic Glass at 375 ~ 500℃ in Dry Air

本研究主要探討銅基塊狀非晶合金（Cu47Ti34Zr11Ni8，以下簡稱Cu470）在375 ~ 500℃空氣下之氧化行為。研究結果顯示，非晶合金之氧化動力學皆呈現二段式拋物線型定律，且氧化速率隨溫度上升而加快。非晶合金在400℃氧化後生成CuO，而在425-450℃時除生成CuO外另有微量的正方晶ZrO2（t-ZrO2）、TiO2與ZrTiO4生成，此外，更有少量TiO在溫度高於475℃時生成。由XRD分析得知，非晶合金基材於400℃氧化後轉變為Cu51Zr14之結晶相，而氧化溫度高於475℃時，非晶合金基材將轉變成為Cu51Zr14、CuTi與CuTi2等三個結晶相；因此可知，氧化溫度與時間會影響Cu47Ti34Zr11Ni8非晶合金氧化反應及相變化行為。

The oxidation behavior of the Cu47Ti34Zr11Ni8 bulk-metallic glass (BMG) was studied over the temperature range of 375 ~ 500 ℃ in dry air. The oxidation kinetics of the glassy alloy generally followed a two-stage parabolic-rate law, and the steady-state parabolic-rate constants (kp values) increased with increasing temperature. The type of scales forming on the alloy is temperature-dependent, and the scales consisted mainly of CuO at 400 ℃, while minor amounts of t-ZrO2, TiO2, and ZrTiO4 formed at 425 ~ 450 ℃ and TiO formed at an even higher temperature of greater than 475 ℃. In addition, the substrate was transformed into a crystalline Cu51Zr14 phase after being oxidized for 24 hrs at 400 ℃, while three crystalline phases of Cu51Zr14, CuTi, and CuTi2 were detected at T ≥ 475 ℃. It was found that the oxidation and phase-transformation behavior of the amorphous alloy was strongly dependent on temperature and duration of time.