Recrystallization Behavior of Single-crystal Hollow Blade Tenon

In order to better understand the effect of the temperature and load on recrystallization behavior of DD5 single-crystal hollow blade tenon, samples with different loads were heat treated at different solution temperatures in a furnace. Optical microscope and scanning electron microscope were used to study the microstructure of recrystallization and size distribution of γ′ phase after solution treatment. Results show that there are no new grains found after solution treatment at 1230 °C/4 h, air cooling. However, the depth of load affected area increases with the bearing load and the size and depth of recrystallized cellular structure with newly-formed γ′ phase particles increase with the load below the solution temperature. Besides, the recrystallized nuclei begin from the dendrite when the solution treatment is 1315 °C/4 h, air cooling. The dendrite arms are passivated and the boundary between dendrite arm and interdendritic space disappear and γ/γ′ phase eutectic structure exists between dendrites in the recrystallization area. Moreover, the recrystallization area and the primary dendritic size gradually increase with the increase in load above the solution temperature.