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
By:  Kevin P. Boyle
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1996
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 51
Description: 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.
Notes: Thesis advisor(s): T.R. McNelley.

"September 1996."

Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, September 1996.

Includes bibliographical references (p. 47-49).

Approved for public release; distribution unlimited.

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US Navy (USN) author.

dk/dk cc:9116 5/14/97