ABSTRACT
The fatigue failure mechanisms of titanium alloy matrix composites and titanium aluminide matrix composites have many commonalities. Isothermal fatigue failure mechanisms associated with fiber-dominated failures, crack initiation at damaged fibers on the specimen edges, and preferential matrix cracking with fiber bridging are activated in 0 degree fiber-reinforced laminates of both classes of titanium matrix composites (TMCs). Silicon carbide and boron fibers have been applied as continuous reinforcement in TMCs with some success. The boron fibers are made by chemical vapor deposition onto tungsten cores. Several basic aspects of monotonic failure mechanisms in TMCs also apply in fatigue loading and are briefly reviewed in the chapter. [0 degree] TMC strength is strongly dictated by the fibers, whereas [90 degree] composite strength is controlled by properties of the fiber-matrix interfaces and matrix.
