Bridgman Growth and Oxidation Behavior of Ni-Base Superalloy Single Crystals

Ni-base superalloy single crystals have been grown by the modified vertical Bridgman method. Using Al₂O₃ ceramics crucible and 〈001〉-orientated seed, single crystals up to 30—40 mm in diameter and 260 mm in length were obtained. Special-shaped Al₂O₃ crucible was used and turbine blades were grown successfully. The morphology demonstrated the typical microstructure of the Ni-base superalloy single crystal with a minor of γ′/γ eutectic in the interdendritic region. The average dendrite arm space was 367 μm and the γ′ phase was cubical and distributed uniformly. The oxidation behavior was investigated at 900 and 1 000 ℃ for 200 h, and the weight gain reached nearly a constant value when oxidized for 120 h.