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Cooperative nucleation of shear dislocation loops
Y Q Sun1, P M Hazzledine, P B Hirsch
1Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Illinois 61801, USA.
Physical Review Letters
|February 28, 2002
Summary
Image stress from subcritical shear loops drives cooperative nucleation, causing rapid instability and generating stable loops. This process requires a relatively high applied shear stress for loop generation.
Area of Science:
- Materials Science
- Solid Mechanics
- Condensed Matter Physics
Background:
- Understanding the behavior of shear loops is crucial for materials science.
- Transient subcritical shear loops form under applied shear stress.
- The elastic interaction between these loops, known as image stress, influences their collective behavior.
Purpose of the Study:
- To investigate the role of image stress in the nucleation and growth of shear loops.
- To determine the conditions under which cooperative nucleation leads to instability.
- To analyze the relationship between image stress, loop density, and applied shear stress.
Main Methods:
- Theoretical analysis of elastic interactions between randomly distributed shear loops.
- Modeling the development of image stress as a function of loop density and applied stress.
- Investigating the instability arising from cooperative nucleation of shear loops.
Main Results:
- The mean image stress is proportional to the volume density of shear loops and has the same sign as the applied stress.
- Image stress promotes cooperative nucleation, leading to an instability.
- This instability results in a rapid increase in loop numbers and image stress, generating stable, expanding loops.
Conclusions:
- Image stress is a key factor in the cooperative nucleation and instability of shear loops.
- The critical applied shear stress for this instability is relatively high.
- The findings provide insights into the mechanisms governing the formation of stable loops in stressed materials.
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