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Notes for High Throughput Analysis of Multicomponent
Multiphase Diffusion Data Workshop May 14&15, 2007
Vam der Ven
Using Green-Kubo formalism to derive kinetic cofficients from fluctuations at equilibrium.
Calculated diffusion coefficients using first principles cluster expansion combined with kinetic Monte Carol simulation for evaluating indivial hops.
Distinction between interstitial and substitutional diffusion
- Interstitial - rigid lattice; example Li diffusion in transition metal oxide host (LixCoO2)
- Two hop mechanisms evaluated: single vacancy hop and divacancy hop.
- Acitivation barrier dependent on composition
- Subtitutional diffusion: example Al-Li ordered alloy
- First principles wants to treat a perfect crystal
- Vacancies make this a ternary problem
- Equilibrium vacancy concnetration (uniform source/sink approximation)
- Kehr et al. Phys Rev B 39, 4891 (1989) can diagonalize D-matrix to get density relaxation contribution and interdiffusin contribution
Mantina
- First principles used to calculate impurity diffusion
- There was some discussion about the relation of solubility limits, references regarding the entropy of migration, and the optimal cell size to use for the calculations. Manjeera has sent the following reference on the entropy of migration as a follow-up to the discussion. pdf file
Mirsa
- Questek is characterzing and mdoeling microstructure evolution in various Ni-base superalloys; γ' MC and TCP precipitation.
- Validating results using epxerimental results from 3-D atom probe results from Seidman's group, from isothermal studies from NASA and from DTA non-isothermal studies from OSU.
- Some discussion about modeling APB energies for the γ´/%gamma;. interface and elastic energy contributions.
Morrison and Mao
- Morrison discussed 3-D atom probe results for the γ´ evolution for a Ni-Al-Cr alloy. Mao demonstrated how monte carlo simulations are used to help interrupt the 3-D atom probe results.
- Additional reference on the work presented was sent by David Seidman.
pdf file
Agren
- Agren discussed of new models in DICTRA for describing diffusion in oxide phases.
- Some follow discussion on whether the models should specifically take into account hole diffusion
Lupulescu
- Lupulescu presented work on teaching tools developed at Union College.
- Discussion highlighted the question about whether to smooth or not to smooth experimental data (composition profiles) before fitting
Morral
- Discussion about notation of concentrations in multiphase region.
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- Link to L. Carol report on interdiffusion in Ni-Al-Cr alloys at 1200 C pdf file
Mason
- Presented new homogenization model in DICTRA and the new molar volume contribution in the new thermodynamic Fe database. There was also some discussion about the stiochoimetric diffusion model in DICTRA.
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