Effects of stacking fault energy on the creep behaviors of Ni-base superalloy |
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| Affiliation: | 1. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK;2. School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK;1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People׳s Republic of China;2. Shandong University, Jinan 250061, People׳s Republic of China;3. Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People׳s Republic of China;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Road, Lanzhou 730000, PR China;2. Department of Superalloys, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, PR China;1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China;2. School of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230026, China;1. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China;2. Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China;3. School of Materials and Metallurgy, Northeast University, Shenyang 110004, People’s Republic of China;1. Department of Materials Science and Engineering, The Ohio State University, 2041 College Road, OH 43210, USA;2. FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124, USA;3. Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK;4. Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, USA |
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| Abstract: | Cobalt in a 23 wt.% Co containing Ni-base superalloys was systematically substituted by Ni in order to study the effects of stacking fault energy (SFE) on the creep mechanisms. The deformation microstructures of the alloys during different creep stages at 725 °C and 630 MPa were investigated by transmission electron microscopy (TEM). The results showed that the creep life increased as the SFE decreased corresponding to the increase of Co content in the alloys. At primary creep stage, the dislocation was difficult to dissociate independent of SFE. In contrast, at secondary and tertiary creep stages the dislocations dissociated at γ/γ′ interface and the partial dislocation started to shear γ′ precipitates, leaving isolated faults (IFs) in high SFE alloy, while the dislocations dissociated in the matrix and the partials swept out the matrix and γ′ precipitates creating extended stacking faults (ESFs) or deformation microtwins which were involved in diffusion-mediated reordering in low SFE alloy. It is suggested that the deformation microtwinning process should be favorable with the decrease of SFE, which could enhance the creep resistance and improve the creep properties of the alloys. |
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| Keywords: | Superalloy Stacking fault energy Isolated fault Extended stacking fault Microtwin |
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