In Situ Observation of Slow Crack Growth in a Whisker-Reinforced Alumina Matrix Composite

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J. Korean Ceram. Soc. > Volume 33(2); 1996 > Article

Journal of the Korean Ceramic Society 1996;33(2): 203.

SiC 휘스커 보강 알루미나 복합재료에서 Slow Crack Growth 현상의 직접관찰 연구

손기선, 김우상, 이성학

포항공과대학교 항공재료연구센터

In Situ Observation of Slow Crack Growth in a Whisker-Reinforced Alumina Matrix Composite

ABSTRACT

In this study the subcritical crack growth behavior in an Al2O3-SiCw composite has been investigated using in situ fracture technique of applied moment double cantilever beam (AMDCB) specimens indside an SEM. This technique allows the detailed observation of whisker and grain bridging in the crack wake region. The experimental results indicated that the KI-a curve was deviated from the conventional powder law form and that the existed a region where the rate of microcrack growth was decreased with increasing the externally applied stress intensity factor. This behavior could be explained by arising crack growth resistance i.e. R-curve behavior which was associated with crack shielding due to whisker and grain bridging. The R-curve was also analyzed from the KI-a curve data in order to quantify the bridging effect in the Al2O3-SiCw composite.

Key words: Subcritical crack growth, In situ fracture technique, R-curve, Grain bridging, Whisker bridging, $K-1$-acurve