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INTERDIFFUSION ANALYSIS FOR NICOCRALY AND NIAL VS. VARIOUS SUPERALLOYS
| Title: | INTERDIFFUSION ANALYSIS FOR NICOCRALY AND NIAL VS. VARIOUS SUPERALLOYS. |
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| Name(s): |
Perez, Emmanuel, Author Sohn, Yong-Ho, Committee Chair University of Central Florida, Degree Grantor |
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| Type of Resource: | text | |
| Date Issued: | 2005 | |
| Publisher: | University of Central Florida | |
| Language(s): | English | |
| Abstract/Description: | Hot section components in gas turbines can be NiCoCrAlY-coated to provide the component with an Al reservoir that maintains a protective oxide layer on its surface. Over the service life of the component, the coatings degrade by composition and phase changes due to oxidation/hot-corrosion, and multicomponent interdiffusion from and into the superalloy substrate. In this study, the rate of Al interdiffusion into selected Ni-base superalloys using various diffusion couples of two-phase NiCoCrAlY (beta + gamma) and single beta-phase NiAl with the selected alloys is measured. The diffusion couples were examined with an emphasis on the composition-dependence of Al interdiffusion. Microstructural analysis of the NiCoCrAlY vs. superalloys couples is performed to examine the dependence of coatings lifetime on the superalloy composition. The beta-NiAl diffusion couples were analyzed to determine the integrated, apparent and average effective interdiffusion coefficient as a function of superalloy's composition. Concentration profiles were obtained by EPMA of the NiAl vs. superalloy diffusion couples. Findings of this study show that the lifetimes of NiCoCrAlY are heavily dependent on superalloy compositions. The rate of interdiffusion in the diffusion couples is affected by the refractory precipitate phase microstructure structures in the interdiffusion zones as well as by component interactions. The results of the beta-NiAl diffusion couples show that increasing concentrations of Cr, Mo and Ti in the superalloy increase the Al effective interdiffusion coefficient into the superalloy, while increasing concentrations of Al, Ta and W reduce it. Thus NiCoCrAlY-superalloy systems may be designed to produce optimal microstructures in the interdiffusion zone and minimize Al interdiffusion by consideration of these diffusional interactions. | |
| Identifier: | CFE0000681 (IID), ucf:46486 (fedora) | |
| Note(s): |
2005-08-01 M.S.M.S.E. Engineering and Computer Science, Department of Mechanical, Materials, and Aerospace Engineering Masters This record was generated from author submitted information. |
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| Subject(s): |
diffusion interdiffusion MCrAlY NiAl NiCoCrAlY superalloy diffusion coefficient refractory |
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| Persistent Link to This Record: | http://purl.flvc.org/ucf/fd/CFE0000681 | |
| Restrictions on Access: | public | |
| Host Institution: | UCF |
