Refined dendrite and precise orientation of nickel-based monocrystal superalloy with melt superheating treatment

Ni-based monocrystal superalloy with fine dendrite, precise orientation and finally elevated service performance is required as turbine blades in advanced aeroengine. In this paper, the melt superheating treatment is carried out for DD3 single crystal superalloy during directional solidification processing. The thermal gradient of solidification interface remains constant for different melt superheating temperatures with the appropriate superheating treatment regulation. It is shown that with the melt superheating temperature increased from 1500°C to 1640°C and then to 1780°C respectively, both the primary and the secondary dendrite arms are obviously refined and the dendrite segregation ratios of Mo, W and Ti are reduced while the deviation angle of (001) crystal orientation can all be controlled within 5. The dendrite structure refinement and the crystal orientation consistence should be attributed to the melt structure change and heredity which is caused by the superheating treatment.