Dendrite Growth Observation of the Ni-based System Using In-situ Synchrotron Imaging

초록

The conventional optical microscopy approach for in-situ observation of metallic solidification faces limitations due to high solidification temperatures and the opacity of solid metal. To address this, our study developed an innovative in-situ imaging technique utilizing a white X-ray source generated from the synchrotron beam line at the Pohang Accelerator Laboratory in Korea. In-situ observation performed using a high-temperature furnace operated at a temperature of 1600°C until the specimen was fully melted under a vacuum pressure of10-3 torr. Subsequently, controlled cooling was achieved by adjusting the current through carbon heaters from -0.2 to -0.8 A/min. Dendrite structure parameters such as tip radius, arm spacing, and mushy zone length, as a function of cooling rates were measured directly from thein-situ images. To correlate dendrite growth behavior with microstructure, we further analyzed the microstructural properties using optical and electron microscopies, as well as atom probe tomography.