Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7971737 | Materials Science and Engineering: A | 2018 | 22 Pages |
Abstract
The current work characterizes the microstructure and mechanical properties of two arc melted Co-Ni-based superalloys containing in atomic percent: 1) Co-40Ni-10Al-7.5W-10Cr-3Ta-0.06B-0.6â¯C and 2) Co-40Ni-10Al-7.5W-10Cr-3Nb-0.06B-0.6â¯C. These two materials named 3Ta and 3Nb, respectively, were characterized by X-Ray diffraction analysis, differential scanning calorimetry, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction and transmission electron microscopy. Furthermore, compression tests were performed from room temperature up to 1000â¯Â°C. The 3Ta and 3Nb alloys showed different as-cast microstructures that were confirmed by microstructural characterization and Scheil simulations. The phase transformation temperatures of minor phases were measured and calculated using a thermodynamic approach and some discrepancies observed on the calculated γâ²-solvus temperatures reflect that the thermodynamic description of γⲠphase does not take into account the strong partition effect of Ta, Nb and Ti into γâ². As shown by DSC results, the γⲠphase was stable for both alloys up to 1000â¯Â°C, being the main reason for the 3Ta and 3Nb alloys to keep the yield stress above 500â¯MPa.
Keywords
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
A.M.S. Costa, J.P. Oliveira, M.V. Salgado, C.A. Nunes, E.S.N. Lopes, N.V.V. Mogili, A.J. Ramirez, A.P. Tschiptschin,