Publication date: Jan 17, 2023
Prismatic slip in magnesium at temperatures T ≲ 150 K occurs at ∼ 100 MPa independent of temperature, and jerky flow due to large prismatic dislocation glide distances is observed; this athermal regime is not understood. In contrast, the behavior at T ≳ 150 K is understood to be governed by a thermally-activated double-cross-slip of the stable basal screw dislocation through an unstable or weakly metastable prism screw configuration and back to the basal screw. Here, a range of neural network potentials (NNPs) that are very similar for many properties of Mg including the basal-prism-basal cross-slip path and pro- cess, are shown to have an instability in prism slip at a potential-dependent critical stress. One NNP, NNP-77, has a critical instability stress in good agreement with experiments and also has basal-prism-basal transition path energies in very good agreement with DFT results, making it an excellent potential for understanding Mg prism slip. Full 3d simulations of the expansion of a prismatic loop using NNP-77 then also show a transition from cross-slip onto the basal plane at low stresses to prismatic loop expansion with no cross- slip at higher stresses, consistent with in-situ TEM observations. These results reveal (i) the origin and prediction of the observed unstable low-T prismatic slip in Mg and (ii) the critical use of machine-learning potentials to guide discovery and understanding of new important metallurgical behavior.
No Explore or Discover sections associated with this archive record.
File name | Size | Description |
---|---|---|
Potentials.zip
MD5md5:363d7d85af875592dee8df1d45ba2c62
|
261.0 KiB | Neural network potentials NNP63 and NNP77 |
Code.zip
MD5md5:2dc31d8e27817ddd3b2d3d4ce580ff76
|
92.8 KiB | Input files for lammps and vasp |
2023.10 (version v1) [This version] | Jan 17, 2023 | DOI10.24435/materialscloud:3f-w3 |