The role of particle cracking in dilatation during tensile straining of a cast and thermomechanically processed 6061 Al - 20 volume percent Al2O3 metal matrix composite
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Authors
Boyle, Kevin P.
Subjects
Composite Materials
MMCs
DRA
Plastic Deformation
TMP
MMCs
DRA
Plastic Deformation
TMP
Advisors
McNelley, Terry R.
Date of Issue
1996-09
Date
September 1996
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
In this work, the dilatation during tensile straining of a cast and thermomechanically processed 6061 Al - Al2O3 metal matrix composite (MMC) containing 20 volume percent of Al2O3 particles was examined. Standard tensile samples of the MMC and unreinforced 6061 Al were machined. Precise diameter measurements were made of both composite and unreinforced samples prior to and immediately following tensile straining. Tension tests were conducted to various strains as well as to fracture and an extensometer was employed to obtain accurate measurement of the axial strain. The MMC material exhibited a continuously increasing dilatation during tensile straining while the unreinforced 6061 control material deformed plastically at constant volume. Careful metallographic preparation revealed particle cracking in all MMC samples throughout the range of strains examined. A clear trend of increased frequency of particle cracking was observed. Void formation and growth due to cracking of the particles was analyzed and shown to correlate with the dilatation observed during tensile straining of the composite. Linkage of such voids is proposed as the mechanism of crack propagation at failure of the MMC.
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
ix, 51 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.