| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Computational Thermodynamics and Kinetics
|
| Presentation Title |
Phase-field Model of Kirkendall Porosity Formation During Ti/Ni Interdiffusion to Form NiTi Microwires |
| Author(s) |
Alexander F. Chadwick, David Dunand, Peter Voorhees |
| On-Site Speaker (Planned) |
Alexander F. Chadwick |
| Abstract Scope |
Recent experimental studies of the formation of NiTi microwires through gas-phase Ti-deposition on Ni wires and homogenization revealed that Ti/Ni interdiffusion (from Ni+Ti to NiTi) is accompanied by a pronounced Kirkendall effect that generates porosity near phase boundaries during Ni/Ti interdiffusion. While phase-field simulations have demonstrated quantitative agreement against experiments for phase transformations in multicomponent alloys, they typically have not included either vacancy transport or porosity formation. We therefore present a grand potential phase-field model of the Ti/Ni interdiffusion process. The vacancy transport and reaction kinetics of the model are verified against sharp-interface descriptions derived through irreversible thermodynamics. We apply the model to the binary NiTi system and examine how the transport of vacancies and atoms, interfacial reaction kinetics, and the geometry of the microwire all affect the predicted porosity in the final microstructure. The simulation results are compared to experiments for validation. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |