鋯銅基塊狀金屬玻璃複合材料高溫氧化行為之探討

The oxidation behavior of a novel Ni-free Zr-Cu-based bulk metallic glass composite

李偉豪(Wei-Hau Li)

指導教授 ： 王惠森

義守大學/理工學院/材料科學與工程學系/碩士(2014年)

https://doi.org/10.6343/ISU.2014.00115

摘要

本研究針對合金成分(Zr48Cu32Al8Ag8,Ta4)Si0.75的鋯銅基塊狀金屬玻璃複合材料(Bulk metallic glass composite, BMGC)，在非晶溫度區間(400oC)、過冷夜相溫度區間(430oC、480oC)以及結晶溫度區間(520oC、560oC)進行100小時高溫氧化試驗，藉以瞭解其高溫氧化行為。
實驗結果顯示，BMGC的氧化動力學遵守兩或三個階段的拋物線行為，在非晶區間，氧化層以t-ZrO2、m-ZrO2、CuO為主以及少量的Ag顆粒，基材維持非晶狀態；在過冷夜相區間，氧化物沒有改變，基材由非晶態開始相變化產生Cu10Zr7；當溫度升高至結晶區間，氧化層內部新增Al2O3氧化物，基材產生Zr2Cu，並在溫度560oC時基材生成AlCu2Zr。
BMGC析出的強化相Ta顆粒，在恆溫氧化過程當中可能在恆溫溫度≥ 480oC與Si產生反應生成化合物Ta2Si，因而在Ta顆粒產生裂縫，除此之外，Ta析出相周圍亦存在一個通道；裂縫及通道的存在造成氧氣分子更容易擴散至未氧化的底材，此現象隨著溫度升高或時間增加亦更加顯著，因此在較高溫氧化試驗最終階段加速其氧化行為。

關鍵字

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並列摘要

The oxidation behavior of a novel Ni-free (Zr48Cu32Al8Ag8,Ta4)Si0.75 bulk metallic glass composite (BMGC) in dry air in the amorphous state(at 400oC), supercooled liquid state (SLS at 430oC and 480oC) and the crystallization state (CS at 520oC and 560oC) for 100 hours were studied herein.
Test results showed that the oxidation kinetics of the BMGC in the amorphous state, SLS and CS followed a multi-stage oxidation rate law. The scales forming in all the amorphous state, SLS and CS consist of t-ZrO2, and m-ZrO2, CuO and Ag. In the CS, additional Al2O3 was observed. In the substrate area, Cu10Zr7 crystalline likely formed in the amorphous substrate in the SLS. In the CS, more crystallization phases were found in the substrate, including additional Zr2Cu observed at temperatures ≥ 520oC; AlCu2Zr was observed at 560oC.
The Ta-reinforced phase in the BMGC was more likely to react with Si in the scales forming Ta2Si at temperatures ≥ 480oC, which resulted in cracks in the Ta. Furthermore, channels between Ta precipitates and the matrix might exist, facilitating oxygen diffusivity. As the oxidation temperature (e.g., CS) and test duration were increased, the effects of the cracks and the channels became more significant and were responsible for the fast-growth oxidation in the final stage of the test.

並列關鍵字

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參考文獻

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