Dislocation Networks and the Microstructural Origin of Strain Hardening
Ryan B Sills1,2, Nicolas Bertin2, Amin Aghaei2
1Sandia National Laboratories, Livermore, California 94551, USA.
Physical Review Letters
|September 8, 2018
Summary
Dislocation junction formation is key to understanding metal strain hardening. Discrete dislocation dynamics simulations reveal glissile junctions significantly contribute to hardening in face-centered cubic copper.
Area of Science:
- Materials Science
- Solid Mechanics
- Computational Physics
Background:
- Plastic deformation in metals involves an increase in dislocation density and microstructural refinement, causing strain hardening.
- Understanding the link between microstructure evolution and macroscopic mechanical properties like strain hardening is crucial.
Purpose of the Study:
- To investigate the fundamental role of junction formation in connecting dislocation microstructure evolution and strain hardening.
- To elucidate the relationship between dislocation network characteristics and the hardening rate in face-centered cubic (fcc) metals.
Main Methods:
- Utilizing discrete dislocation dynamics (DDD) simulations.
- Analyzing the resulting dislocation network structure and its statistical properties.
Main Results:
- Dislocation network segments follow an exponential length distribution, a consequence of junction formation.
- Junction formation can be modeled as a one-dimensional Poisson process.
- Two non-dimensional parameters govern microstructure evolution, and stable junction formation rate dictates hardening rate.
Conclusions:
- Glissile junctions are identified as the primary contributors to strain hardening in fcc crystals.
- The study provides a quantitative link between dislocation microstructure and macroscopic strain hardening behavior.
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