ACOUSTIC-EMISSION DURING FATIGUE-CRACK PROPAGATION IN SIC PARTICLE-REINFORCED AL MATRIX COMPOSITES

The acoustic emission (AE) behavior during fatigue propagation in alum inum 6061 and aluminum 6061 matrix composites containing 5, 10, and 20 wt pct SIC particle reinforcement was investigated under tension-tens ion fatigue loading. The purpose of this investigation was to monitor fatigue crack propagation by the AE technique and to identify the sour ce(s) of AE. Most of the AEs detected were observed at the top of the load cycles. The cumulative number of AE events was found to correspon d closely to the fatigue crack growth and to increase with increasing SiC content. Fractographic studies revealed an increasing number of fr actured particles and to a lesser extent decohered particles on the fa tigue fracture surface as the crack propagation rate (e.g., Delta K) o r the SiC content was increased.