Spatially Resolved MicroDiffraction Analysis of the Plastic Deformation in the Shock Recovered Al Single Crystal

Conference · Sat Dec 31 23:00:00 EST 2005

OSTI ID:1003525

Barabash, Rozaliya ^[1]; Ice, Gene E ^[1]; Liu, W. ^[2]; Belak, J. ^[3]; Kumar, M. ^[3]

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1. ORNL
2. Argonne National Laboratory (ANL)
3. Lawrence Livermore National Laboratory (LLNL)

Strong shock waves result in the transition from elastic to plastic compression. As a result of dislocation motion and the strong interaction between dislocations and elastic waves, an initially random dislocation distribution becomes unstable and forms a correlated dislocation arrangement into dislocation walls. Some fraction of the dislocations may remain randomly distributed, and the rest form various correlated groupings and more organised disclination arrangements. Regions with geometrically necessary dislocations may form causing local lattice curvature. Aluminum has been the object of numerous shock experiments. Reshock and release of shock - compressed aluminum was studied previously by Lipkin and Asay1. Recently developed in-situ time resolved x-ray diffraction relates in-situ pseudo Kossel line broadening with dislocation density during the shock experiments2 - 4. Effect of stress triaxiality on void growth in dynamic fracture of metals was studied with molecular dynamic simulations5. We complement these results with white (polychromatic) X-ray microbeam study of the meso-scale geometrically necessary dislocation arrangement in the (123) Al single crystal. The single crystal Al samples were shocked to incipient spallation fracture on the LLNL light gas gun as was done by Stevens et.al. A spatially resolved diffraction method with a sub micrometer-diameter beam and 3D differential aperture technique together with MD simulations, SEM and OIM analysis are applied to understand the arrangements of voids, geometrically necessary dislocations and strain gradient distribution in samples of Al (123) single crystal shocked to incipient spallation fracture. We describe how geometrically necessary dislocations and effective strain gradient alter white beam Laue patterns of the shocked materials. We show how to quantitatively determine the orientation and density of geometrically necessary dislocations in the shock recovered Al samples being initially oriented for single slip.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003525
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ALUMINIUM
APERTURES
COMPRESSION
DEFORMATION
DIFFRACTION METHODS
DISLOCATIONS
DISTRIBUTION
FRACTURES
LAWRENCE LIVERMORE NATIONAL LABORATORY
LINE BROADENING
MONOCRYSTALS
ORIENTATION
PLASTICS
SHOCK WAVES
SLIP
SPALLATION
STRAINS
STRONG INTERACTIONS
X-RAY DIFFRACTION