Superplastic Deformation Behavior and Microstructure Evolution of(TiB+La₂O₃)/IMI834 Titanium-Based Composite

Superplastic deformation of (TiB+La₂O₃)/IMI834 titanium-based composite was carried out. The effects of different temperatures (850, 900, 950, 1 000 ℃) and initial strain rates (0.000 5, 0.001 0, 0.005 0 s^-1) on its superplastic deformation behavior and microstructure were studied. The results show that the composite was composed of α-Ti, TiB, La₂O₃ and dispersed (TiZr)_xSi particles. The composite exhibited perfect superplasticity, and showed the largest elongation of 505% at 900 ℃ and 0.001 0 s^-1. The strain rate sensitivity coefficient of the composite was higher than 0.30. The flow stress and deformation activation energy increased with the strain rate. With the increase of the deformation degree, the α phase of lamellar layer was gradually equiaxed, the small-angle grain boundary changed to the high-angle grain boundary, while the hole defects increased. Grain boundary sliding, grain rotation and dynamic recrystallization were the main deformation mechanisms of the superplastic deformation of (TiB+La₂O₃)/IMI834 titanium-based composite.