Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high γ’ volume fraction
| Autor: | David C. Dunand, Jacques Perrin Toinin, Ding-Wen Chung, David N. Seidman, Eric A. Lass |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Mechanical Engineering Alloy Metals and Alloys Intermetallic Analytical chemistry chemistry.chemical_element 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Superalloy Chromium chemistry Creep Mechanics of Materials Volume fraction Materials Chemistry engineering Solvus 0210 nano-technology Cobalt |
| Zdroj: | Journal of Alloys and Compounds. 832:154790 |
| ISSN: | 0925-8388 |
| DOI: | 10.1016/j.jallcom.2020.154790 |
| Popis: | Chromium is known to confer oxidation resistance on Co-based superalloys. Herein we studied the influence of Cr concentration on the properties of a Co-based superalloy, Co–30Ni–11Al–2Ti-5.5W-2.5Ta-0.1B (at.%), with high γ ’ -volume fractions (up to 98%). Additions of 4, 8, or 12 at.% Cr decreased the γ ’ -solvus temperature and the γ ’ -volume fraction, while also reducing the mean radius of γ ’ -particles. Synchrotron X-ray diffraction and atom-probe tomography confirmed that Cr reduces the lattice parameter misfit by altering the partitioning behavior of W between the γ- and γ ’ -phases. Concomitantly, an increase in Cr content significantly improved the oxidation resistance of the alloy. The results indicate that 4 at.% Cr is sufficient to decrease the oxidation rate by two orders of magnitude. A creep study at 850 ∘C revealed that Cr does not affect adversely the creep performance in high γ ’ -volume fraction Co-based superalloys, but the tendency toward γ ’ rafting changes with Cr concentration. Compared to Ni3Al intermetallic compounds, the alloys with high γ ’ -volume fraction studied exhibited a significantly higher creep resistance. This may be attributed to the increase in antiphase boundary energy caused by the addition of Cr, Ti, or Ta, and significant solid-solution hardening in the Co-based intermetallic γ ’ -phase. |
| Databáze: | OpenAIRE |
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