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Compressive Deformation and Yielding Mechanisms in Cellular Al Alloys Determined Using X-ray Tomography and Surface Strain Mapping

Published online by Cambridge University Press:  10 February 2011

H. Bart-Smith ,
A.-F. Bastawros ,
D. R. Mumm ,
A. G. Evans ,
D. J. Sypeck  and
H. N. G. Wadley
H. Bart-Smith
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
A.-F. Bastawros
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
D. R. Mumm
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
A. G. Evans
Affiliation:
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
D. J. Sypeck
Affiliation:
School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22903
H. N. G. Wadley
Affiliation:
School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22903
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Abstract

The mechanisms of compressive deformation that occur in closed cell Al alloys have been established. This has been achieved by using x-ray computed tomography (CT) and surface strain mapping to determine the deformation modes and the cell morphologies that control the onset of yielding. The deformation is found to localize in narrow bands having width of order of a cell diameter. Outside the bands, the material remains elastic. The cells within the bands that experience large permanent strains are primarily elliptical. A group of cells work collectively to allow large localized deformation. Size does not appear to be the initiator of the deformation bands. Equiaxed cells remain elastic. The implications for manufacturing materials with superior mechanical properties are discussed. Visualization of internal deformation of a closed cell Al alloy core, as part of a sandwich panel construction, is also possible using x-ray tomography. Preliminary results for a punch indentation test are presented.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 521: Symposium R – Porous & Cellular Materials for Structural Applications , 1998 , 71
Copyright
Copyright © Materials Research Society 1998

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