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Nanovoid cavitation by dislocation emission in aluminum
Jaime Marian1, Jaroslaw Knap, Michael Ortiz
1Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA.
Physical Review Letters
|November 5, 2004
Summary
Nanovoid growth in aluminum involves distinct pressure stages and yield points. These stages are characterized by the formation and dissolution of dislocation structures, leading to the emission of dislocation loops.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Materials Science
Background:
- Understanding nanovoid formation and growth is crucial for predicting material behavior under stress.
- Hydrostatic tension plays a significant role in void evolution in metals.
- Dislocation dynamics are fundamental to plastic deformation and fracture mechanisms.
Purpose of the Study:
- To determine the transition pathways for nanovoid growth in aluminum under hydrostatic tension.
- To investigate the energy minimization pathways at 0 K.
- To elucidate the role of dislocation structures in void evolution.
Main Methods:
- Utilized the quasicontinuum method to model aluminum, mitigating boundary effects.
- Employed the Ercolessi-Adams embedded-atom method for atomic-scale simulations.
- Performed energy minimization calculations at 0 Kelvin.
Main Results:
- Identified multiple stages of pressure buildup separated by distinct yield points.
- Observed the formation of stable tetrahedral dislocation junctions at the initial yield point.
- Documented the dissolution of tetrahedral structures and emission of dislocation loops at the second yield point.
Conclusions:
- The nanovoid growth process in aluminum under tension is a multi-stage phenomenon.
- Tetrahedral dislocation junctions play a critical role in the initial stages of void expansion.
- The emission of both conventional and anomalous dislocation loops signifies key transitions in void growth.
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