Length scales and scale-free dynamics of dislocations in dense solid solutions

The fundamental interactions between an edge dislocation and a random solid solution are studied by analyzing dislocation line roughness profiles obtained from molecular dynamics simulations of Fe 0.70 Ni 0.11 Cr 0.19 over a range of stresses and temperatures. These roughness profiles reveal the hal...

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Bibliographic Details
Published in:Materials theory 2020-11, Vol.4 (1), p.1-25, Article 6
Main Authors: Péterffy, Gábor, Ispánovity, Péter D., Foster, Michael E., Zhou, Xiaowang, Sills, Ryan B.
Format: Article
Language:English
Subjects:
Bowing
Characterization and Evaluation of Materials
Characterization of Dislocation Ensembles: Measures and Complexity
Chemistry and Materials Science
Condensed Matter Physics
Correlation
Depinning transition
Dislocation
Dislocation density
Dislocation mobility
Edge dislocations
Materials Engineering
MATERIALS SCIENCE
Mobility
Molecular dynamics
Original Article
Physical Chemistry
Random noise
Roughness
Solid solutions
Solute
Solution strengthening
Strengthening
Temperature dependence
Yield stress
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Summary:The fundamental interactions between an edge dislocation and a random solid solution are studied by analyzing dislocation line roughness profiles obtained from molecular dynamics simulations of Fe 0.70 Ni 0.11 Cr 0.19 over a range of stresses and temperatures. These roughness profiles reveal the hallmark features of a depinning transition. Namely, below a temperature-dependent critical stress, the dislocation line exhibits roughness in two different length scale regimes which are divided by a so-called correlation length. This correlation length increases with applied stress and at the critical stress (depinning transition or yield stress) formally goes to infinity. Above the critical stress, the line roughness profile converges to that of a random noise field. Motivated by these results, a physical model is developed based on the notion of coherent line bowing over all length scales below the correlation length. Above the correlation length, the solute field prohibits such coherent line bow outs. Using this model, we identify potential gaps in existing theories of solid solution strengthening and show that recent observations of length-dependent dislocation mobilities can be rationalized.
ISSN:2509-8012
2509-8012
DOI:10.1186/s41313-020-00023-z