Study of Geometrically Necessary Dislocations of a Partially Recrystallized Aluminum Alloy Using 2D EBSD

During recrystallization, the growth of fresh grains initiated within a deformed microstructure causes dramatic changes in the dislocation structure and density of a heavily deformed matrix. In this paper, the microstructure of a cold rolled and partially recrystallized Al-Mg alloy (AA5052) was stud...

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Bibliographic Details
Published in:Microscopy and microanalysis 2019-06, Vol.25 (3), p.656-663
Main Authors: Seyed Salehi, Majid, Anjabin, Nozar, Kim, Hyoung S.
Format: Article
Language:English
Subjects:
Alloys
Aluminum
Aluminum alloys
Aluminum base alloys
Annealing
Boundaries
Cold
Cold rolling
Continuum mechanics
Crystal lattices
Curvature
Deformation mechanisms
Dislocation
Dislocation density
Electron backscatter diffraction
Grain boundaries
Grains
Materials Applications
Mathematical analysis
Microstructure
Optimization techniques
Recrystallization
Symmetry
Tensors
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Summary:During recrystallization, the growth of fresh grains initiated within a deformed microstructure causes dramatic changes in the dislocation structure and density of a heavily deformed matrix. In this paper, the microstructure of a cold rolled and partially recrystallized Al-Mg alloy (AA5052) was studied via electron backscattered diffraction (EBSD) analysis. The structure and density of the geometrically necessary dislocations (GNDs) were predicted using a combination of continuum mechanics and dislocation theory. Accordingly, the Nye dislocation tensor, which determines the GND structure, was estimated by calculation of the lattice curvature. To do so, five components of the Nye dislocation tensor were directly calculated from the local orientation of surface points of the specimen, which was determined by two-dimensional EBSD. The remaining components of GNDs were determined by minimizing a normalized Hamiltonian equation based on dislocation energy. The results show the elimination of low angle boundaries, lattice curvature, and GNDs in recrystallized regions and the formation of low angle boundaries with orientation discontinuities in deformed grains, which may be due to static recovery.
ISSN:1431-9276
1435-8115
DOI:10.1017/S1431927619000382