Abstract
To enhance the creep resistance at elevated temperatures, a new precipitation-strengthened CuCrNbZr alloy has been designed and fabricated to achieve a target microstructure with coarse Laves_Cr2Nb precipitates at grain boundaries and fine Cr-rich precipitates in the matrix. This work systematically studied the creep property of the CuCrNbZr alloy at 500 °C under 90–140 MPa applied stress and compared to that of a reference commercial CuCrZr alloy without Laves_Cr2Nb precipitates. Microstructures before and after creep testing were investigated by optical and transmission electron microscopy. Based on the creep testing and microstructural characterization results, the dominant creep mechanism in both alloys was grain boundary sliding with a threshold stress of ~80 MPa. The CuCrNbZr alloy has higher creep strength and higher creep fracture ductility, and longer creep life than the CuCrZr alloy. The improved creep property in the CuCrNbZr alloy was due to the presence of Laves_Cr2Nb precipitates that efficiently impede the crack propagation.
| Original language | English |
|---|---|
| Article number | 139110 |
| Journal | Materials Science and Engineering: A |
| Volume | 779 |
| DOIs | |
| State | Published - Mar 27 2020 |
Funding
The authors acknowledge the financial support by the United States Department of Energy (DOE), Office of Fusion Energy Sciences. Research conducted by University of Tennessee-Battelle, LLC, under contract No. DE-AC05-00OR22725 and by UTK (grant # DE-SC0006661) with the U.S. DOE. L. Wang is also particially supported by University of Tennessee graduate research fellowship. Y. Yang would like to thank Cecil Carmichael, Tom Geer and Yukinori Yamamoto at ORNL for making the ingot, conducting optical microscopy and microhardness tests and helping with inert gas environment of the creep tests. L. Wang acknowledges Low Activation Materials Development and Analysis facility (LAMDA) for TEM characterization. D. Sprouster acknowledges Brookhaven National Laboratory's National Synchrotron Light Source-II (NSLS-II) for XRD analysis. L. Wang and C. Zheng thank Dr. Yang Liu for assistance with the FEI Titan experiments at the Analytical Instrumentation Facility (AIF). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI). L. Wang would also like to thank Drs. Meimei Li from Argonne National Laboratory and Tianyi Chen from ORNL for the fruitful discussions on the manuscript. The authors acknowledge the financial support by the United States Department of Energy (DOE), Office of Fusion Energy Sciences . Research conducted by University of Tennessee-Battelle, LLC, under contract No. DE-AC05-00OR22725 and by UTK (grant # DE-SC0006661 ) with the U.S. DOE. L. Wang is also particially supported by University of Tennessee graduate research fellowship. Y. Yang would like to thank Cecil Carmichael, Tom Geer and Yukinori Yamamoto at ORNL for making the ingot, conducting optical microscopy and microhardness tests and helping with inert gas environment of the creep tests. . L. Wang acknowledges Low Activation Materials Development and Analysis facility (LAMDA) for TEM characterization. D. Sprouster acknowledges Brookhaven National Laboratory’s National Synchrotron Light Source-II (NSLS-II) for XRD analysis. L. Wang and C. Zheng thank Dr. Yang Liu for assistance with the FEI Titan experiments at the Analytical Instrumentation Facility (AIF). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI). L. Wang would also like to thank Drs. Meimei Li from Argonne National Laboratory and Tianyi Chen from ORNL for the fruitful discussions on the manuscript.
Keywords
- Creep
- Laves_CrNb precipitates
- Microstructural characterizations
- Precipitate-strengthened Cu alloy