添加Er對Zr55Cu30Al10Ni5非晶合金氧化行爲之影響

Effect of Er Addition on the Oxidation of Zr55Cu30Al10Ni5 Bulk Amorphous Alloys

蕭智鴻(Z. H. Shiao) ； 林品辰(P. C. Lin) ； 任一飛(I. F. Jen) ； 謝心心(H. H. Hsieh) ； 開物(W. Kai)

《防蝕工程》 23卷4期 (2009/12) Pp. 271-278

https://doi.org/10.6376/JCCE.200912.0271

摘要

本研究探討添加少量(2 at.%)Er對Zr55Cu30Al10Ni5塊狀非晶合金（以下簡稱Zr2Er-BMG）在溫度350~500℃之乾空氣下氧化行爲。由實驗結果顯示，Zr2Er-BMG的氧化動力學遵守二至三階段的拋物線律，且非晶的氧化動力學常數（k(下標 p)值）在結晶溫度(T(下標 x)=473.2℃)之下時，會隨溫度上升而增加，但在溫度475~500℃時，k(下標 p)值反而降低，此外，Zr2Er-BMG的氧化速率會比未添加Er非晶更快，顯示添加Er促進非晶的氧化反應。Zr2Er-BMG的氧化生成物因溫度不同而異，在350℃ 時大部分爲tetragonal ZrO2(t-ZrO2)及少部分monoclinic ZrO2 (m-ZrO2)、及CuO；而當溫度大於400℃，更有少量的Al2O3產生，而在T(下標 g)點以上時，m-ZrO2量會隨溫度上升而增加。當添加2%Er時，將有可能使Er(上标 +3)離子取代少量Zr(上标 +4)離子，進而增加氧離子的空孔濃度，使得氧離子內部擴散速率增加，致使Zr2Er-BMG的氧化速率比未添加Er的Zr55Cu30Al10Ni5非晶的氧化速率更快。此外，溫度在400℃及425℃時，基材結晶相爲Zr2Cu；溫度大於450℃時，基材結晶相爲CuZr2及Al2Zr3，顯示非晶氧化後，基材伴隨有結晶相變化發生。

關鍵字

拋物線律 ； 非晶合金 ； 鉺

並列摘要

The oxidation behavior of a (Zr55Cu30Al10Ni5) 98Er2 bulk metallic glass (Zr2Er-BMG) was studied over the temperature range of 350~500℃ in dry air. The results showed that the oxidation kinetics of the Zr2Er-BMG followed a two-to-three-stage parabolic-rate law. The parabolic rate constant (k(subscript p) values) generally increased with increasing temperature when it was below the crystalline temperature (T(subscript x)=473.2℃), while the k(subscript p) values fluctuated at temperatures above T(subscript x). It was found that the addition of 2% Er enhanced the oxidation rate of the Zr2Er-BMG, as compared to that of the Er-free glassy alloy. The scales formed on the Zr2Er-BMG were strongly dependent on temperature, consisting exclusive tetragonal ZrO2 (t-ZrO2) at 350℃, while minor amounts of monoclinic ZrO2 (m-ZrO2), CuO, and Al2O3 were detected at T＞400℃. The amounts of m-ZrO2 increased with increasing temperature when it is above T(subscript g) In addition, the BMG substrate began to form crystalline Zr2Cu and Al2Zr3 beneath the scales after being oxidized at T ＞400℃. It is most likely that the addition of 2% Er increased the concentration of oxygen vacancies in the defective ZrO2-lattice, which in turn enhanced inward diffusion of oxygen and led to the higher oxidation rate of the Zr2Er-BMG.

並列關鍵字

Parabolic-rate law ； Bulk metallic glasses ； Er