Topic：On the application of in-situ X-ray imaging techniques in solidification science

Speaker：Prof.  Ragnvald H. Mathiesen

　　　　Department of Physics, Norwegian University of Science and Technology (NTNU), Norway

Time：10:00—12:00 am., (Friday) July 13, 2018

Venue：Room 403, Shi Changxu Building

Abstract：

Over the last 2-3 decades, X-ray imaging techniques have become well-established methods for in situ studies of solidification microstructure formation in metals and alloys. From the pioneering start with X-radiography limited to spatial resolutions of a few microns at about 1 Hz frame rates, state-of-the art methods of today can provide spatial resolutions beyond 100 nm and full tomographic acquisitions in 100 ms, or radiography beyond 1 kHz frame rates. The seminar will give an overview over various dedicated solidification studies carried out over this period, such as columnar and equiaxed dendritic growth, phase separation and coagulation dynamics in immiscible melts, dendrite fragmentation and coarsening, grain growth in weld pools, dendritic growth under coupled diffusive and convective transport control and pattern formation and growth of regular and irregular eutectics. The seminar will also provide an overview of the different X-ray methods applicable to in situ studies of solidification phenomena, including their special merits and advantages. These will comprise X-radiography, X-tomography, X-topography, ultra-fast polychromatic XRD, as well as X-ray transmission microscopy.