| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
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| Symposium
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Atomistic Simulations Linked to Experiments to Understand Mechanical Behavior: A MPMD Symposium in Honor of Professor Diana Farkas
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| Presentation Title |
Mobile Dislocation Mediated Hall-Petch and Inverse Hall-Petch Behaviors in Nanocrystalline Al-Doped Boron Carbide |
| Author(s) |
Jun Li, Kun Luo, Qi An |
| On-Site Speaker (Planned) |
Qi An |
| Abstract Scope |
The Hall-Petch and inverse Hall-Petch behaviors in nanocrystalline ceramics are poorly understood due to limited dislocation activities. We utilize molecular dynamics simulations with a machine-learning force field to study the shear deformation behaviors of nanocrystalline Al-doped boron carbide (n-B12-CAlC) across varying grain sizes. A transition from Hall-Petch to inverse Hall-Petch behavior is observed when grain size reaches a critical value of 6.09 nm, with a maximum shear strength of 14.93 GPa. This transition is driven by mobile dislocations nucleated from grain boundaries (GBs) due to the breakage of weakened C-Al chain bonds. As grain size decreases, the increasing GB regions homogenize shear stress, suppressing dislocation nucleation and strengthening the material. However, further reduction in grain size (<6 nm) increases favorable sites for dislocation nucleation, reducing shear strength and triggering inverse Hall-Petch behavior. These insights elucidate the deformation mechanisms in nanocrystalline ceramics and explain the Hall-Petch to inverse Hall-Petch transition. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Ceramics, Machine Learning, Modeling and Simulation |