隔热挡板厚度对DD6单晶高温合金凝固组织的影响

Effects of Thermal Baffle Thickness on the Solidification Microstructure of Single Crystal Superalloy DD6

单晶凝固过程中隔热挡板的控制对温度梯度及温度场均匀性有重要影响,进而会影响到单晶凝固组织,因此需要对隔热挡板进行研究。采用第二代单晶高温合金DD6,研究了不同厚度隔热挡板对DD6单晶高温合金凝固组织的影响。结果表明,随着隔热挡板厚度增加,单晶凝固过程中温度梯度降低,但晶体生长方向与[001]偏离度变小。此外,随着隔热挡板厚度增加,DD6单晶高温合金一次枝晶间距增大,γ-γ′共晶含量和尺寸增加,枝晶干与枝晶间的铸态γ′尺寸略有增加,合金主要元素偏析加大。

The control of thermal baffle has an important role in the temperature gradient and the homogeneous temperature field in the process of single crystal superalloy solidification as a result of affecting the solidification microstructures of the single crystal superalloy, so it is necessary to analyze the thermal baffle. Influences of different thermal baffle thickness on the solidification microstructures of the second generation single crystal superalloy DD6 were investigated. The results reveal that with increasing in the thickness of thermal baffle, the temperature gradient is decreased in the process of single crystal superalloy solidification, while the angle between the single crystal growth orientation and the[OO1] orientation is narrowed. In addition, as the thermal baffle thickness increases, the primary dendrite arm spacing is increased, and the size and the volume fraction of γ-γ＇ eutectie are increased too. Meanwhile, the size of γ＇ phase in the primary dendrite and in the interdendrite is increased slightly accompanying with the increase of segregation ratio of main elements.