Abstract
The fatigue crack growth behavior in SiC (SCS-6) fiber reinforced Ti-15-3 matrix alloy composite subjected to a constant tension-tension loading mode was studied using single edge specimen in 2×(10)^<-3> Pa vacuum at 293 and 823K, with a frequency of 2 Hz, and a stress ratio of R=0.1. Direct measurement of the fatigue crack length, and the crack opening displacement along the crack wake during the test were carried out by SEM. The increase in the test temperature was found to lead to a decrease in the fatigue crack growth rate. The degradation of bridging fibers in the crack wake was severe for T=293K, and this behavior was dependent of the test temperature. The crack opening displacement along the crack wake tested at T=823K decreased with increasing crack length, and this tendency is dependent on the applied stress range. The associated increase in the crack tip shielding is explained on the basis of the crack closure due to the matrix relaxation by fatigue creep and the interface wear behavior.
