Abstract:The TiC/Cu-Al₂O₃ composite was prepared by vacuum-pressed and internal oxidation sintering. The microstructures were observed and the main strengthening mechanisms were analyzed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The hot deformation of the composite was investigated by the Gleeble-1500D thermal simulator. The tests were performed at the temperature of 450-850 ℃, the strain rate of 0.001-1 s^-1 and the maximum strain of 0.7. According to the ln θ -ε curves and the -？(ln θ)/？ε-ε curves, the critical conditions of dynamic recrystallization and the volume fraction of dynamic recrystallization were obtained by the computation of the work hardening rate (θ) from initial true stress-true stain data. Based on the volume fraction of the dynamic recrystallization of the composite, the dynamic recrystallization kinetic equation was established. The results show that the strength of the composite is enhanced by the dispersion of the g-Al₂O₃ particles and the amorphous layer between TiC and substrate. There exists the softening mechanism of dynamic recrystallization during the hot compression process. The volume fraction of dynamic recrystallization of the composite increases with the increase of the plastic strain and the deformation temperature, as well as the decrease of the strain rate.

Key words: TiC/Cu-Al₂O₃ composite; strengthening mechanism; hot deformation; dynamic recrystallization