Low-cycle fatigue behavior of Al-based composites containing in situ TiB2, Al2O3 and Al3Ti reinforcements

Aluminum-based composites reinforced with in situ TiB2 and Al2O3 particles were prepared through reactive hot pressing of TiO2, Al and B powders. Brittle Al3Ti blocks were also formed in situ when the B/TiO2 molecular ratio is smaller than 2. The low-cycle fatigue behavior of in situ composites under total strain-controlled conditions at room temperature was investigated. The results showed that the composite reinforced with in situ TiB2 and Al2O3 particles exhibits a relatively stable cyclic response at low total strain amplitudes. At higher total strain amplitudes, cyclic softening from the onset of deformation was observed. However, the presence of AbTi blocks led to a very slight cyclic hardening followed by softening at total strain amplitude of 0.4%. Moreover, the intermetallic Al3Ti blocks reduced the fatigue life of in situ composites as they promoted microscopic cracking during cyclic deformation. Finally, the fatigue life data of in situ composites can be described by the Coffin-Manson relationship. (C) 2003 Elsevier Science B.V. All rights reserved.