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

Abstract

Dynamic recrystallization (DRX) mechanism of the primary α phase (αp) and β phases in the isothermal compression of TiBw 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 αp and β phases due to the existence of TiBw. The αp recrystallized grains derived from the deformed αp grains either near or away from TiBw were attributed to the continuous dynamic recrystallization (CDRX) mechanism, in which the TiBw accelerated the recrystallization process of the neighboring αp grains. The evolution of β phase away from TiBw displayed the typical discontinuous dynamic recrystallization (DDRX) features. While the β phase near TiBw underwent the CDRX, where the TiBw reinforcements accelerated the accumulation of dislocations and the occurrence of rapid dynamic recovery (DRV). In particular, the effect of TiBw on the DRX was discussed in detail by considering the special crystal structure of TiBw. 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.