Cyclic fatigue of Ce-TZP/Al{sub 2}O{sub 3} composites: Role of the degradation of transformation zone shielding

Journal Article · Wed Mar 01 04:00:00 EST 1995 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1995.tb08221.x· OSTI ID:79772

Tsai, J F; Shetty, D K ^[1]

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1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering

The origin of cyclic fatigue in two Ce-TZP/Al{sub 2}O{sub 3} composites was investigated by (a) measurements of residual stresses in the transformation zones and crack-tip stress intensities in in situ loaded compact specimens using microprobe Raman spectroscopy, (b) examination of the crack-tip transformation zones by transmission electron microscopy, and (c) measurements of crack-growth rates in cyclic fatigue and in sustained loading at 400 C, a temperature at which stress-induced transformation of the tetragonal zirconia to the monoclinic polymorph was suppressed. Transformation zones formed during cyclic fatigue consistently showed lower compressive residual stresses and higher crack-tip stress intensities than the zones formed in sustained loading. Transmission electron microscopy revealed monoclinic laths of smaller average twin spacing and of multiple types of lattice correspondence in the transformation zones of the fatigue specimens as compared to the sustained-load specimens. Crack-growth measurements at 400 C indicated a significant suppression of the cyclic fatigue effect in the absence of transformation plasticity. These results in combination pointed to degradation of transformation-zone shielding as an important contributing cause of cyclic fatigue in Ce-TZP/Al{sub 2}O{sub 3} composites. A more efficient accommodation of the transformation strains within the zones appears to be the underlying mechanism of the degradation of zone shielding in cyclic fatigue.

• Sponsoring Organization: USDOE
• OSTI ID: 79772
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 3 Vol. 78; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CERIUM OXIDES
COMPOSITE MATERIALS
CRACK PROPAGATION
CRACKS
CRYSTAL-PHASE TRANSFORMATIONS
FATIGUE
RAMAN SPECTROSCOPY
RESIDUAL STRESSES
STRESS INTENSITY FACTORS
TRANSMISSION ELECTRON MICROSCOPY
ZIRCONIUM OXIDES