Cyclic deformation behavior of in situ aluminum–matrix composites of the system Al–Al 3Ti–TiB 2–Al 2O 3

Abstract

Aluminum-based composites reinforced with in situ ceramic TiB 2 and Al 2O 3 particulates as well as intermetallic Al 3Ti phase were prepared through reactive hot pressing of powders from the Al–TiO 2–B 2O 3 and Al–TiO 2–B systems. In situ composite derived from the Al–TiO 2–B 2O 3 system exhibited lower yield and tensile strengths but higher tensile ductility due to its lower Al 3Ti content. The low cycle fatigue behavior of in situ composites prepared from such systems under total strain-controlled conditions at room temperature was investigated. At low strain amplitudes, stable cyclic response was observed in the in situ composites fabricated from the Al–TiO 2–B 2O 3 and Al–TiO 2–B systems. However, initial cyclic hardening followed by softening occurred in the composite prepared from Al–TiO 2–B 2O 3 system. The fatigue damage was observed to initiate in brittle Al 3Ti blocks. Thus composite fabricated from Al–TiO 2–B 2O 3 system had longer fatigue lives. The fatigue life data of in situ composites can be described by the Coffin–Manson relationship.