Free energy change of a dislocation due to a Cottrell atmosphere

R. B. Sills, W. Cai

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The free energy reduction of a dislocation due to a Cottrell atmosphere of solutes is computed using a continuum model. We show that the free energy change is composed of near-core and far-field components. The far-field component can be computed analytically using the linearized theory of solid solutions. Near the core the linearized theory is inaccurate, and the near-core component must be computed numerically. The influence of interactions between solutes in neighbouring lattice sites is also examined using the continuum model. We show that this model is able to reproduce atomistic calculations of the nickel–hydrogen system, predicting hydride formation on dislocations. The formation of these hydrides leads to dramatic reductions in the free energy. Finally, the influence of the free energy change on a dislocation’s line tension is examined by computing the equilibrium shape of a dislocation shear loop and the activation stress for a Frank–Read source using discrete dislocation dynamics.

Original languageEnglish (US)
Pages (from-to)1491-1510
Number of pages20
JournalPhilosophical Magazine
Issue number16
StatePublished - Jun 3 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


  • Dislocations
  • dislocation dynamics
  • hydrogen
  • solid solutions


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