Effects of tantalum on the temporal evolution of a model Ni–Al–Cr superalloy during phase decomposition
| Autor: | David N. Seidman, Ronald D. Noebe, Christopher Booth-Morrison |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Materials science
Nanostructure Polymers and Plastics Scanning electron microscope Metallurgy Alloy Metals and Alloys Tantalum chemistry.chemical_element Thermodynamics Atom probe engineering.material Decomposition Electronic Optical and Magnetic Materials law.invention Superalloy chemistry law Phase (matter) Ceramics and Composites engineering |
| Zdroj: | Acta Materialia. 57:909-920 |
| ISSN: | 1359-6454 |
| Popis: | The effects of a 2.0 at.% addition of Ta to a model Ni-10.0Al-8.5Cr (at.%) superalloy aged at 1073 K are assessed using scanning electron microscopy and atom-probe tomography. The gamma'(Ll2)-precipitate morphology that develops as a result of gamma-(fcc)matrix phase decomposition is found to evolve from a bimodal distribution of spheroidal precipitates, to {001}-faceted cuboids and parallelepipeds aligned along the elastically soft {001}-type directions. The phase compositions and the widths of the gamma'-precipitate/gamma-matrix heterophase interfaces evolve temporally as the Ni-Al-Cr-Ta alloy undergoes quasi-stationary state coarsening after 1 h of aging. Tantalum is observed to partition preferentially to the gamma'-precipitate phase, and suppresses the mobility of Ni in the gamma-matrix sufficiently to cause an accumulation of Ni on the gamma-matrix side of the gamma'/gamma interface. Additionally, computational modeling, employing Thermo-Calc, Dictra and PrecipiCalc, is employed to elucidate the kinetic pathways that lead to phase decomposition in this concentrated Ni-Al-Cr-Ta alloy. |
| Databáze: | OpenAIRE |
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