Theoretical investigation of the 70.5° mixed dislocations in body-centered cubic transition metals

Lorenz Romaner, Tapaswani Pradhan, Anastasiia Kholtobina, Ralf Drautz, Matous Mrovec

Research output: Contribution to journalArticleResearchpeer-review


The low-temperature plasticity of body-centered cubic (bcc) metals is governed by [Formula presented] screw dislocations due to their compact, non-planar core. It has been proposed that 70.5 ° mixed (M111) dislocations may also exhibit special core structures and comparably large Peierls stresses, but the theoretical and experimental evidence is still incomplete. In this work, we present a detailed comparative study of the M111 dislocation in five bcc transition metals on the basis of atomistic simulations. We employ density functional theory and semi-empirical interatomic potentials to investigate both the core structure and the Peierls barrier of the M111 dislocation. Our calculations demonstrate that reliable prediction of M111 properties presents not only a very stringent test for the reliability of interatomic potentials but is also challenging for first-principles calculations for which careful convergence studies are required. Our study reveals that the Peierls barrier and stress vary significantly for different bcc transition metals. Sizable barriers are found for W and Mo while for Nb, Ta and Fe the barrier is comparably small. Our predictions are consistent with internal friction measurements and provide new insights into the plasticity of bcc metals.

Original languageEnglish
Article number117154
Number of pages10
JournalActa materialia
Issue number15 September
Early online date13 Jul 2021
Publication statusPublished - 15 Sept 2021

Bibliographical note

Publisher Copyright: © 2021 Acta Materialia Inc.

Cite this