Dislocation dynamics of face-centered cubic metals and alloys
Abstract/Contents
- Abstract
- Face-centered cubic (FCC) metals and alloys—such as aluminum, copper, and austenitic stainless steel—are ubiquitous in the automotive, aerospace, and oil and gas industries. To further our understanding of the nature of plastic deformation in these materials, we have utilized dislocation dynamics (DD) simulations. We begin with a study of time integration in dislocation dynamics, examining the time-step-limiting aspects of DD, and developing a new subcycling-based time integrator that improves efficiency 100-fold. We then utilize this time integrator to study the basics of plasticity in pure, single crystalline copper. DD simulations were run over a wide range of strain rates and initial dislocation densities, examining how the yield strength and hardening rate vary, and making comparisons against the available experimental data. A detailed study on the contribution of binary dislocation junctions to hardening is then presented, showing that these junctions are an essential ingredient for hardening to occur. We then go on to study the most common strengthening mechanisms employed in FCC metals: solid solution strengthening and precipitation strengthening. After deriving the suitable chemical potential for the solute atoms comprising a solid solution, the influence of an "atmosphere" of solutes surrounding a dislocation on the stress field and line tension of the dislocation are examined, showing that these effects are generally small. The drag force exerted on dislocations by their atmospheres is then studied. We find these drag forces are often larger than those due to lattice friction, and can influence plasticity in FCC materials significantly. To study precipitation strengthening, a new algorithm for simulating dislocation-precipitate interactions is developed, which allows for ellipsoidal inclusions with arbitrary aspect ratio and arbitrary misfit. The new formulation is used to study Orowan looping in overaged aluminum-copper alloys, which have plate-like precipitates. The results and methods presented here constitute a broad set of advancements towards a more sound understanding of plastic deformation in FCC metals and alloys.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Sills, Ryan B |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering. |
| Primary advisor | Cai, Wei |
| Thesis advisor | Cai, Wei |
| Thesis advisor | Balch, Dorian K |
| Thesis advisor | Lew, Adrian |
| Thesis advisor | Nix, William D |
| Advisor | Balch, Dorian K |
| Advisor | Lew, Adrian |
| Advisor | Nix, William D |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Ryan B. Sills. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Ryan Barton Sills
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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