Polymorphic structure of ⟨a⟩-type screw dislocation cores in α-Ti

D Jany and E Rothchild and DC Chrzan, PHYSICAL REVIEW MATERIALS, 7, 103603 (2023).

DOI: 10.1103/PhysRevMaterials.7.103603

The dislocation core structure has a significant role in determining the dominant slip plane and the magnitude of the Peierls stress for a dislocation. An important challenge when studying dislocation cores is to determine the stable and metastable core morphologies, and then relate these structures to the dynamics of the dislocations. This study introduces a method for identifying core structures that are metastable at zero temperature. Application of this method to < a >-type screw dislocations in alpha-Ti (as described using an empirical potential) reveals a multitude of (meta)stable nonplanar cores. Molecular dynamics studies show how the competing metastable core structures determine the properties of the dislocations at temperature and under a range of non- Schmid stresses.

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