Comparison of the Isothermal Oxidation Behavior of As-Cast Cu鈥?7%Cr and Cu鈥?7%Cr鈥?%Al Part I: Oxidation Kinetics
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- 作者：S. V. Raj
- 关键词：Isothermal oxidation ; Cu– ; Cr alloys ; Cu– ; Cr– ; Al ; Copper alloys ; Oxidation kinetics
- 刊名：Oxidation of Metals
- 出版时间：August, 2008
- 出版年：2008
- 期刊代码：48_0030770X
- 类别：law
- 卷：70
- 期：1-2
- 页码：85-102
- 数据来源：sp
摘要
The isothermal oxidation kinetics of as-cast Cu–17%Cr and Cu–17%Cr–5%Al in air were studied between 773 and 1,173 K under atmospheric pressure. These observations reveal that Cu–17%Cr–5%Al oxidizes at significantly slower rates than Cu–17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu–17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 卤 9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu–17%Cr–5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu–17%Cr–5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.