Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

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• 作者：Zhiqi Yao ; Craig C. Degnan ; Mark A. E. Jepson…
• 刊名：Metallurgical and Materials Transactions A
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：47
• 期：12
• 页码：6330-6338
• 全文大小：1,542 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Materials Science
  Metallic Materials
  Structural Materials
  Physical Chemistry
  Ceramics,Glass,Composites,Natural Materials
  
• 出版者：Springer Boston
• ISSN：1543-1940
• 卷排序：47

文摘

The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the ‘channels’ between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.