Dislocation -Obstacle Interactions in Aluminum Alloys
Clark, Blythe Gore
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https://hdl.handle.net/2142/82786
Description
Title
Dislocation -Obstacle Interactions in Aluminum Alloys
Author(s)
Clark, Blythe Gore
Issue Date
2006
Doctoral Committee Chair(s)
Robertson, Ian M.
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
This thesis examines two types of dislocation-obstacle interactions: dislocation-particle interactions during creep deformation, and dislocation-loop interactions during deformation at room temperature. Dislocation-particle interaction studies in Al-Zn-Mg-Cu-Zr, Al-4Mg-0.3Sc, and Al-0.3Sc showed that temperature, coherency, and particle size play a role in determining the dominant bypass mechanism, and that interactions are more complex than what is considered in current models. A new mechanism for elevated temperature bypass of particles during creep deformation was revealed, in which dislocations interact directly with the particle-matrix interface, altering the interfacial structure, and affecting subsequent dislocation interactions. These results are discussed in relation to macroscopic behavior in steady-state creep experiments. In addition, dislocation-loop interaction studies show interactions to be of two types: intersection and elastic interactions. In-situ observations show annihilation, rotation, and repulsion of loops due to dislocation interactions. Comparison with current molecular dynamics simulations highlights the need to better understand these interactions in order to improve models for irradiated materials.
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