Accession Number : ADA324274

Title :   The Role of Particle Cracking in Dilatation During Tensile Straining of a Cast and Thermomechanically Processed 6061 A1-20 Volume Percent AL2O3 Metal Matrix Composite.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Boyle, Kevin P.

PDF Url : ADA324274

Report Date : SEP 1996

Pagination or Media Count : 61

Abstract : 1In 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.

Descriptors :   *PLASTIC DEFORMATION, *THERMOMECHANICS, *METAL MATRIX COMPOSITES, DIAMETERS, TENSILE STRENGTH, ALUMINUM ALLOYS, THESES, STRAIN(MECHANICS), VOIDS, CRACK PROPAGATION, PARTICLES, ALUMINUM OXIDES, METALLOGRAPHY, EXTENSOMETERS.

Subject Categories : Laminates and Composite Materials
      Fabrication Metallurgy
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE