LOW CYCLE FATIGUE OF (Al₂O₃+TiB₂+Al₃Ti)/Al COMPOSITES FABRICATED BY REACTIVE HOT PRESSING

Aluminum-based composites reinforced with in-situ Al₂O₃, TiB₂ and Al₃Ti particles were prepared through reactive hot pressing from Al, B₂O₃ and TiO₂ powders and Al, B and TiO₂ powders. There is fine Al₃Ti precipitation in composite fabricated by Al, B, TiO₂ powders. The low cycle fatigue behavior of in-situ composites was investigated under total strain-controlled conditions at the room temperature. The composite free of precipitation Al₃Ti phase exhibits a stable cyclic response at lower total strain amplitudes. The cyclic hardening in the first cycle followed by cyclic softening occurs in the composite free of precipitation at higher total strain amplitudes.The composite containing Al₃Ti phase exhibits a stable cyclic response at all amplitudes adopted in the study. The sets of crack initiation are broken Al₃Ti phase, the debonded interface between Al₃Ti phase and matrix, and microcracks in the matrix. The cracks propagate through the matrix, passing by Al₂O₃ and TiB₂ particles. The fatigue life of two composites can be described by the Coffin-Manson relationship.