Microstructural Evolution and Deformation Mechanisms of in-situ TiC Reinforced Ti-6Al-4V Composites during High-Temperature Hot Compression

Deformation processing is a key strategy to improve the strength and ductility of metal structural materials, especially metal matrix composites. Herein, TiC/Ti‐6Al‐4V (TiC/TC4) composites with discontinuous network structures were in‐situ spark plasma sintered using reinforcement precursors of reduced graphene oxide to reinforce TC4 matrix. In order to investigate the hot deformation behaviors and mechanisms of Ti matrix composites, the designed TiC/TC4 composites were hot compressed over temperature range of 870 ∽ 1070 oC and strain range of 0.001 ∽ 10 s‐1. The results indicate the optimal processing window of hot deformation are mainly within the temperature range of 890 ∽ 970 oC and the strain rate range of 0.01 s‐1 ∽ 0.1 s‐1. The flow instability of TiC/TC4 composites occurs in the temperature range of 890 ∽ 930 oC and 1000 ∽ 1060 oC at the strain rate range from 0.1 s‐1 ∽ 10 s‐1. The thermal activation energies of TiC/TC4 composites in the (α+β) and β‐phase regions are 528.22 kJ/mol and 524.24 kJ/mol, respectively. The thermal deformation mechanism of TiC/TC4 composites in the processing window region involves a combination of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). The pinning effect of TiC can effectively hinder the dislocation motion, leading to the generation of high‐density dislocations around TiC. Consequently, this promotes sub‐grains formation and rotation, facilitating CDRX. Meanwhile, TiC particle induces high‐angle grain boundary migration and provides more nucleation sites for recrystallized grains. Hence, TiC impedes the growth of recrystallized grains, promoting the formation of fine equiaxed grain through DDRX. These findings enhance understand the role of hot deformation behaviors of Ti matrix composites and provide insights for their deformation processing.