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arXiv · 2306.10836

Finite-temperature screw dislocation core structures and dynamics in $\alpha$-titanium

Anwen Liu·Tongqi Wen·Jian Han·David J. Srolovitz
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Abstract

A multiscale approach based on molecular dynamics (MD) and kinetic Monte Carlo (kMC) methods is developed to simulate the dynamics of an $\langle \mathbf{a} \rangle$ screw dislocation in $\alpha$-Ti. The free energy barriers for the core dissociation transitions and Peierls barriers for dislocation glide as a function of temperature are extracted from the MD simulations (based on Machine Learning interatomic potentials and optimization); these form the input to kMC simulations. Random walk dislocation trajectories from kMC agree well with those predicted by MD. On some planes, dislocations move via a locking-unlocking mechanism. Surprisingly, some dislocations glide in directions that are not parallel with the core dissociation direction. The MD/kMC multiscale method proposed is applicable to dislocation motion in simple and complex materials (not only screw dislocations in Ti) as a function of temperature and stress state.

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Anwen Liu, Tongqi Wen, Jian Han, David J. Srolovitz. 2023-06-19. Finite-temperature screw dislocation core structures and dynamics in $\alpha$-titanium. https://doi.org/10.1038/s41524-023-01181-7

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