Science and Technology on Advanced High Temperature Structural Materials Laboratory, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
To meet the development needs of advanced aeroengines, the structure of aeroengine turbine blades is becoming increasingly complex, and the content of refractory elements is increasing in single crystal superalloys, which are the preferred materials for turbine blades. As a result, the tendency to form the grain defects increases during the preparation of single crystal turbine blades, which directly affects the quality of single crystal turbine blades. In this paper, a kind of grain defect that appears in the directional solidification process of single crystal superalloys—freckle was discussed. The research works on the formation mechanism, the criterion model and the control method of freckles formation during the directional solidification of single crystal superalloys in recent years was reviewed. The influence of the alloy composition, blade structure, directional solidification process and crystal orientation of single crystal castings on the formation of freckles was analyzed. Considering the influence of the alloying elements in different alloy systems and the parameters of the directional solidification process on the freckle formation, further studying the freckle formation mechanism of the single crystal turbine blade with complex structures, establishing an effective method for prediction and control of freckles are the future research directions.
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2021, Vol. 49 
), 刘世忠, 赵金乾, 史振学, 王效光, 杨万鹏, 岳晓岱
