In Situ Observation of Three-Dimensional Solidification Microstructure of Superalloy Melt Based on X-Ray Stereo Imaging

The use of synchrotron radiation X-ray imaging, with its high spatiotemporal resolution and strong penetration capabilities, holds significant promise for the in situ observation of three-dimensional microstructure evolution during the solidification of superalloy melts. However, the conventional computed tomography (CT) imaging technique has limitations for capturing the dynamic solidification of superalloy melts because of the limitations of in situ solidification equipment. This work introduces a synchrotron radiation X-ray stereo imaging technique that facilitates the swift acquisition of three dimensional spatial data. Based on the principles of binocular parallax, the stereo imaging method leverages projections obtained from two distinct angles to derive depth information about a specific region of interest. This approach boasts notable enhancements in data acquisition speed and image reconstruction when compared with CT techniques. Notably, this work introduces the relationship between binocular projection disparity and depth information and it validates the method's effectiveness by using a static spiral wire sample with a known depth relationship. The experimental results unequivocally establish that the proposed method offers high-resolution capabilities in lateral and longitudinal directions. Finally, the X-ray stereo imaging technique is successfully deployed for the three-dimensional characterization of the solidification process in superalloy melts. It effectively overcomes the challenges posed by the in situ heating device that hinder conventional CT imaging, facilitating the successful reconstruction of the orientation relationship of the solidified microstructure in the thickness direction.