Heterogeneous dynamic recrystallization in the isothermal compression of Ti55-TiB_w composite in α + β region

Dynamic recrystallization (DRX) mechanism of the primary α phase (α_p) and β phases in the isothermal compression of TiB_w reinforced Ti55 composite in the α + β region was investigated by characterizing the grain boundaries misorientation, local strain, subgrain/grain and dislocation morphologies. The results showed the significant heterogenous DRX in both α_p and β phases due to the existence of TiB_w. The α_p recrystallized grains derived from the deformed α_p grains either near or away from TiB_w were attributed to the continuous dynamic recrystallization (CDRX) mechanism, in which the TiB_w accelerated the recrystallization process of the neighboring α_p grains. The evolution of β phase away from TiB_w displayed the typical discontinuous dynamic recrystallization (DDRX) features. While the β phase near TiB_w underwent the CDRX, where the TiB_w reinforcements accelerated the accumulation of dislocations and the occurrence of rapid dynamic recovery (DRV). In particular, the effect of TiB_w on the DRX was discussed in detail by considering the special crystal structure of TiB_w. It was shown that the DRX grains tended to appear next to the incoherent interfaces (101)_TiB, (101¯)_TiB or the sharp curvature edges, such as tips and growth steps of the whiskers due to the stronger hindering effect for dislocation movement in these regions.