| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Chemistry and Physics of Interfaces
|
| Presentation Title |
Grain Boundaries in NiTi Shape Memory Alloys as Host Sites for Martensite Nuclei |
| Author(s) |
Gabriel Plummer, Mikhail Mendelev, Othmane Benafan, John Lawson |
| On-Site Speaker (Planned) |
Gabriel Plummer |
| Abstract Scope |
Shape memory alloys (SMAs) exhibit unique thermomechanical properties due to a reversible martensitic transformation. Microstructural features, such as grain boundaries (GBs), play an important role in determining how the transformation nucleates and propagates, making an understanding of their fundamental physics critical for controlling SMA properties. We performed molecular dynamics simulations examining several symmetric tilt GBs in the austenite phase of NiTi. Among these, the Σ9 (114) GB is notable for its ability to host stable martensite nuclei above the transformation temperature. Upon cooling or applying strain, austenite-martensite phase boundaries can grow out from these GBs with a significantly reduced barrier, indicating a potential strategy for producing SMAs with reduced hysteresis and improved fatigue resistance. Additionally, free energy calculations show that a negative entropy is a fundamental characteristic of these GBs, an anomalous behavior for fixed composition GBs which can be directly linked to the martensitic transformation. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Phase Transformations, Computational Materials Science & Engineering, Modeling and Simulation |