Speculation on the creep behavior of silicon carbide whisker-reinforced alumina

Technical Report · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6785532

Donaldson, K Y; Venkateswaran, A; Hasselman, D P; Rhodes, J F

The creep behavior of SiC whisker-reinforced alumina matrix composites at 1500 deg C was investigated. The creep strain vs time exhibited typical primary, secondary,and tertiary creep. The initial creep rate in the primary regime exhibited a stress exponent of I.59, which is typical for single-phase polycrystalline alumina. The apparent stress exponent for secondary (Steady-state) creep was found to have a value of 2.88, well in excess of the expected value for creep of the alumina matrix. The presence of the whiskers appeared to suppress cavitation or other damage, thereby eliminating any contribution from elastic creep by crack growth or crack-enhanced creep to the total creep deformation. An analysis of the creep behavior of a short elastic fiber-reinforced matrix based on the theory of Kelly and Street was carried out.The results of this analysis suggested that stress dependent sliding at the SiC-alumina interface and stress dependent partial whisker fracture, with associated decrease in the average value of aspect ratio, appear to be the most likely mechanisms responsible for the high value of the apparent stress exponent in the secondary regime.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (USA). Dept. of Materials Engineering
• OSTI ID: 6785532
• Report Number(s): AD-A-219073/4/XAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ASPECT RATIO
BEHAVIOR
CARBIDES
CARBON COMPOUNDS
CAVITATION
CHALCOGENIDES
COMPOSITE MATERIALS
CRACK PROPAGATION
CREEP
CRYSTALS
DEFORMATION
ELASTICITY
MATERIALS
MECHANICAL PROPERTIES
MONOCRYSTALS
OXIDES
OXYGEN COMPOUNDS
POLYCRYSTALS
REINFORCED MATERIALS
SILICON CARBIDES
SILICON COMPOUNDS
STRESSES
TENSILE PROPERTIES
WHISKERS