Dynamic Recrystallization-Related Interface Phase Boundary Migration of TC17/TC4 Bond with Initial Equiaxed Microstructure

The phase, grain, orientation and local misorientation in the bonding interface of a TC17/TC4 bond at different bonding times were carefully investigated via electron backscatter diffraction technique. Dynamic recrystallization (DRX) occurred in the primary α (α_p)-enriched region of the TC4 side, in which large α_p grains of the TC4 side transformed into small recrystallized α grains with random orientation. With the increasing of bonding time, DRX in the α_p -enriched region of the TC4 side was more evident and the recrystallized α grains grew. The stored energy difference between the recrystallized α grains of the TC4 side and the β grains/subgrains of the TC17 side provided the driving force for the migration of the interface phase boundary (IPB). In addition, the migration of IPB was promoted as the bonding time increased, which was due to the synergistic effect of the increase in the stored energy difference and the growth of the recrystallized α grains of the TC4 side.