Solidification behavior of Pt-containing 718Plus superalloy
(1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. Gaona Aero Material Co., Ltd., Beijing 100081, China;
3. Superalloy Department, Central Iron and Steel Research Institute, Beijing 100081, China;
4. Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China)
2. Gaona Aero Material Co., Ltd., Beijing 100081, China;
3. Superalloy Department, Central Iron and Steel Research Institute, Beijing 100081, China;
4. Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China)
Abstract: Solidification behaviors of Pt-containing 718Plus superalloys were studied by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), differential scanning calorimetry (DSC) and simulation calculations. It is found that Pt increases solidification range and decreases solidus temperature of the alloy and precipitation temperature of Laves + γ eutectic phase since Pt enlarges the region of γ phase by increasing Nb solubility. In addition, Pt segregates to the interdendritic region and increases the segregation of Nb and Ti in the interdendritic region due to the strong attractive interactions between Pt and Nb/Ti. As a result, Pt promotes the precipitation of the Laves + γ eutectic phase and η phase around eutectic phase. The increase of solidification range and segregation degrees of Nb and Al caused by Pt also promotes the precipitation and growth of γ'''' + γ" phase around eutectic phase. These results provide experimental bases for understanding the mechanism of Pt in solidification behavior of superalloys.
Key words: platinum; solidification behavior; 718Plus superalloy; eutectic