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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2021
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2108.05438 |
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| _version_ | 1866909302655025152 |
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| author | Baik, Sung-Il Mao, Zugang Ren, Qingqiang Xue, Fei Campbell, Carelyn E. Zhang, Chuan Zhou, Bicheng Noebe, Ronald D. Seidman, David N. |
| author_facet | Baik, Sung-Il Mao, Zugang Ren, Qingqiang Xue, Fei Campbell, Carelyn E. Zhang, Chuan Zhou, Bicheng Noebe, Ronald D. Seidman, David N. |
| contents | The temporal evolution of ordered gamma-prime(L12)-precipitates and the compositional trajectories during phase-separation of the gamma(face-centered-cubic(f.c.c.)) and gamma-prime(L12)-phases are studied in a Ni-0.10Al-0.085Cr-0.02Re(mole-fraction) superalloy, utilizing atom-probe tomography, transmission electron microscopy, and the Philippe-Voorhees (PV) coarsening model. As the gamma-prime(L12)-precipitates grow, the excesses of Ni, Cr and Re, and depletion of Al in the gamma(f.c.c.)-matrix develop as a result of diffusional fluxes crossing gamma(f.c.c.)/gamma-prime(L12) heterophase interfaces. The coupling effects on diffusional fluxes was introduced (PV coarsening model) in terms of the diffusion tensor, D, and the second-derivative tensor of the molar Gibbs free energies, G", obtained employing Thermo-Calc and DICTRA calculations. The Gibbs interfacial free energies are (6.9 +- 1.4) mJ/m2 with all terms in D and G", which changes to (18.9 +- 2.1) mJ/m2, (37.7 +- 3.3) mJ/m2, and (-7.5 +- 1.2) mJ/m2 without including the off-diagonal terms in D, G", and both D and G", respectively. The experimental APT compositional trajectories are displayed and compared with the PV model in a partial quaternary phase-diagram, employing a tetrahedron. The compositional trajectories measured by APT exhibit curvilinear behavior in the nucleation and growth regimes, which become vectors, moving simultaneously toward the gamma(f.c.c.) and gamma-prime(L12) conjugate solvus-surfaces, for the quasi-stationary coarsening regime. The compositional trajectories are compared to the PV model with and without the off-diagonal terms in D and G". The directions including the off-diagonal terms in D and G" tensors are consistent with the APT experimental data. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2108_05438 |
| institution | arXiv |
| publishDate | 2021 |
| record_format | arxiv |
| spellingShingle | The effects of diffusional couplings on compositional trajectories and interfacial free energies during phase separation in a quaternary Ni-Al-Cr-Re model superalloy Baik, Sung-Il Mao, Zugang Ren, Qingqiang Xue, Fei Campbell, Carelyn E. Zhang, Chuan Zhou, Bicheng Noebe, Ronald D. Seidman, David N. Materials Science The temporal evolution of ordered gamma-prime(L12)-precipitates and the compositional trajectories during phase-separation of the gamma(face-centered-cubic(f.c.c.)) and gamma-prime(L12)-phases are studied in a Ni-0.10Al-0.085Cr-0.02Re(mole-fraction) superalloy, utilizing atom-probe tomography, transmission electron microscopy, and the Philippe-Voorhees (PV) coarsening model. As the gamma-prime(L12)-precipitates grow, the excesses of Ni, Cr and Re, and depletion of Al in the gamma(f.c.c.)-matrix develop as a result of diffusional fluxes crossing gamma(f.c.c.)/gamma-prime(L12) heterophase interfaces. The coupling effects on diffusional fluxes was introduced (PV coarsening model) in terms of the diffusion tensor, D, and the second-derivative tensor of the molar Gibbs free energies, G", obtained employing Thermo-Calc and DICTRA calculations. The Gibbs interfacial free energies are (6.9 +- 1.4) mJ/m2 with all terms in D and G", which changes to (18.9 +- 2.1) mJ/m2, (37.7 +- 3.3) mJ/m2, and (-7.5 +- 1.2) mJ/m2 without including the off-diagonal terms in D, G", and both D and G", respectively. The experimental APT compositional trajectories are displayed and compared with the PV model in a partial quaternary phase-diagram, employing a tetrahedron. The compositional trajectories measured by APT exhibit curvilinear behavior in the nucleation and growth regimes, which become vectors, moving simultaneously toward the gamma(f.c.c.) and gamma-prime(L12) conjugate solvus-surfaces, for the quasi-stationary coarsening regime. The compositional trajectories are compared to the PV model with and without the off-diagonal terms in D and G". The directions including the off-diagonal terms in D and G" tensors are consistent with the APT experimental data. |
| title | The effects of diffusional couplings on compositional trajectories and interfacial free energies during phase separation in a quaternary Ni-Al-Cr-Re model superalloy |
| topic | Materials Science |
| url | https://arxiv.org/abs/2108.05438 |