ZrNiAl塊狀非晶之氧化行為研究

Oxidation Behavior of Zr53Ni23.5Al23.5 Bulk Amorphous Alloy

本研究主要探討鋯基非晶合金（Zr53Ni23.5Al23.5，以下均為at.%），在400 ~ 625℃的空氣下氧化行為。研究結果顯示非晶合金之氧化動力學在400 ~ 500℃中遵守單一式拋物線律，且氧化速率隨溫度上升而加快；而在550 ~ 625℃則呈現兩段式拋物線律，但氧化速率隨溫度上升而減緩。非晶合金氧化後在T≤450℃時，其氧化層主要是正方晶之ZrO2 （t-ZrO2）及α-Al2O3；但T > 450℃時，則有t-ZrO2和單斜晶之ZrO2 （m-ZrO2）及Al2O3；由XRD分析得知，非晶合金在550℃氧化30分鐘之基材有Zr2Ni、Zr2Al及ZrNiAl三種結晶相產生，顯示非晶合金經高溫氧化後已有基材相變化發生。

The oxidation behavior of a Zr-based bulk amorphous alloy (BMG, Zr53Ni23.5Al23.5 in at%) was studied over the temperature range 400 ~ 625 ℃ in dry air. The oxidation kinetics of the BMG alloy generally followed a single stage parabolic rate law at 400 ~ 500 ℃, in which the oxidation rates increased with increasing temperature, while two-stage kinetics was noted at 550 ~ 625 ℃, in which the oxidation rates decreased with increasing temperature. In general, the scales formed on the surface of BMG were temperature-dependent, consisting of tetragonal-ZrO2 (t-ZrO2) and Al2O3 at T ≤ 450 ℃, while mostly t-ZrO2 and minor amounts of monoclinic-ZrO2 (m-ZrO2) and Al2O3 were detected at T > 450 ℃. Based on XRD analyses, three crystalline phases of Zr2Al, Zr2Ni, and ZrNiAl were observed for the BMG alloy after oxidation at 550 ℃ for 30min, indicating that phase transformation was taken place.