Cyclic Fatigue‐Crack Growth in a SiC‐Whisker‐Reinforced Alumina Ceramic Composite : Long‐ and Small‐Crack Behavior

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)759-771
Journal / PublicationJournal of the American Ceramic Society
Volume75
Issue number4
Online publishedApr 1992
Publication statusPublished - Apr 1992
Externally publishedYes

Abstract

The ambient‐temperature subcritical growth behavior of both long and microstructurally small cracks is investigated during cyclic‐fatigue loading in a SiC‐whisker‐reinforced alumina (Al2O3–SiCw) ceramic composite (fracture toughness, Kc∼ 4.5 MPa·m1/2). Based on long‐crack experiments using compact C(T) specimens, cyclic fatigue‐crack growth rates (over the range 10−11 to 10−5 m/cycle) are found to be sensitive to the applied stress‐intensity range and load ratio, and to show evidence of fatigue crack closure. Similar to other ceramic materials, under tension–tension loading the “long” (> 3 mm) crack fatigue threshold, ΔKTH, was found to be on the order of 60% of Kc. Conversely, “small” (1 to 300 μm) cracks grown from micro‐indents on the surface of cantilever‐beam specimens were observed to grow at applied ΔK levels some 2 to 3 times smaller than ΔKTH. similar to behavior widely reported for metallic materials. The observed small‐crack behavior is rationalized in terms of the residual stress field associated with the indent, and the restricted role of crack‐tip shielding (from mechanisms such as crack bridging, closure and deflection) with cracks of limited wake, analogous to closure effects with small fatigue cracks in metals. Consistent with the lack of zone‐shielding mechanisms in Al2O3–SiCw, under variable‐amplitude cyclic loading crack‐growth rates do not exhibit the marked transient response following block overload sequences as do transformation‐toughened ceramics or ductile metallic materials. Possible mechanisms for cyclic crack advance in reinforced ceramic‐matrix composite materials are discussed. Copyright © 1992, Wiley Blackwell. All rights reserved

Research Area(s)

  • alumina, crack growth, cyclic fatigue, silicon carbide, whiskers

Citation Format(s)

Cyclic Fatigue‐Crack Growth in a SiC‐Whisker‐Reinforced Alumina Ceramic Composite : Long‐ and Small‐Crack Behavior. / Dauskardt, Reinhold H.; James, M. R.; Porter, J. R.; Ritchie, R. O.

In: Journal of the American Ceramic Society, Vol. 75, No. 4, 04.1992, p. 759-771.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review