High temperature behavior of Al{sub 2}O{sub 3}: SiC nanocomposites

Conference · Fri Sep 01 04:00:00 EDT 1995

OSTI ID:99190

Thompson, A M; Fang, J; Chan, H M; Harmer, M P ^[1]

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1. Lehigh Univ., Bethlehem, PA (United States)

Three aspects of the high temperature behavior of Al{sub 2}O{sub 3}, and Al{sub 2}O{sub 3}:SiC {open_quotes}nanocomposites{close_quotes} (Al{sub 2}O{sub 3} Containing 5 vol% of 0.15 {mu}m SiC particles) have been studied, namely: (1) crack healing of indentation-induced flaws, (2) relaxation of residual stress surrounding a Vickers indentation and (3) tensile creep. Annealing for 2 hours in argon at 1300{degrees}C produces a modest reduction in residual stress and some crack healing in the nanocomposite whereas, in Al{sub 2}O{sub 3} the residual stress is completely relaxed and the cracks grow. The differences in behavior are attributed to differences in fracture mode and dislocation pinning caused by the SiC particles. The results support a previous hypothesis that the strengthening and apparent toughening in these nanocomposites arises from machining-induced residual surface stresses and the healing of machining flaws during annealing. The addition of 5 vol% SiC particles also reduces the tensile creep rate of fully-dense Al{sub 2}O{sub 3} by 2-3 orders of magnitude.

• OSTI ID: 99190
• Report Number(s): CONF-940911--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
ANNEALING
CRACKS
CREEP
DISLOCATION PINNING
MICROSTRUCTURE
PROCESSING
SILICON CARBIDES
STRESSES