Creep behavior in SiC whisker-reinforced alumina composite

Technical Report · Sat Oct 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10188601· OSTI ID:10188601

Lin, H T; Becher, P F ^[1]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

Grain boundary sliding (often accompanied by cavitation) is a major contributor to compressive and tensile creep deformation in fine-grained aluminas, both with and without whisker-reinforcement. Studies indicate that the creep response of alumina composites reinforced with SiC whiskers can be tailored by controlling the composite microstructure and composition. The addition of SiC whiskers (< 30 vol%) significantly increases the creep resistance of fine-grained (1--2 {mu}m) alumina in air at temperatures of 1,200 and 1,300 C. However, at higher whisker contents (30 and 50 vol%), the creep resistance is degraded due to enhanced surface oxidation reactions accompanied by extensive creep cavitation. Densification aids (i.e., Y{sub 2}O{sub 3}), which facilitate silica glass formation and thus liquid phase densification of the composites, can also result in degradation of creep resistance. On the other hand, increasing the matrix grain size or decreasing the whisker aspect ratio (increased whisker number density) results in raising the creep resistance of the composites. These observations not only explain the variability in the creep response of various SiC whisker-reinforced alumina composites but also indicate factors that can be used to enhance the elevated temperature performance.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10188601
• Report Number(s): CONF-9408175--1; ON: DE95001071
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603
ALUMINIUM OXIDES
CHEMICAL COMPOSITION
COMPOSITE MATERIALS
CREEP
EXPERIMENTAL DATA
GRAIN SIZE
HEAT RESISTANT MATERIALS
MECHANICAL PROPERTIES
SILICON CARBIDES