Fatigue behavior of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites

Results of fatigue flexure tests are presented for a Ti-15V-3Cr composite with cross-ply reinforcement by continuous silicon carbide fibers. Four stages of deflection behavior during the fatigue tests are identified. The deflection increased slightly with fatigue cycling at stage I and increased significantly at stage II; at stage III, the deflection again increased negligibly with fatigue cycling; stage IV was associated with final failure, and the deflection increased abruptly. Cracks began to initiate and progressed at stage II; at stage III, significant crack deflection, branching, and fiber bridging were observed, which slowed down the crack driving force. The breakage of fibers during stage IV significantly increased deflection. (AIAA)