日期：2021/12/22 - 2021/12/22
主讲人：Yujun Xie, postdoctoral fellow in the Department of Nuclear Engineering at UC Berkeley
High performance materials associated with efficient manufacturing process play a deterministic role in sustainable energy systems such as advanced nuclear reactor and rechargeable battery. However, the ever-harsher environments in these future technologies often involved extreme temperatures cycling, mechanical stress and irradiation. These significantly challenge the design and manufacturing process for materials beyond the limitation today, which simultaneously require in-depth understanding of the microstructural evolution and degradation mechanism during operation.
In this talk, Dr. Xie will present his work on developing advanced transmission electron microscopy (TEM) techniques with a particular interest in two model systems: metallic glass (inorganic) and organic electrolyte (organic) under extreme environments. First, I will show how in situ heating TEM can reproduce the solidification and crystal growth mechanisms in additive manufacturing process at unprecedented temporal and spatial resolution. Based on the principles, we also demonstrated the capability to fine-tune the mechanical behaviors of the metallic glass under irradiation. Second, I will introduce our development of integrated method combing cryo-TEM with four dimensional-scanning transmission electron microscopy (4D-STEM) techniques and on the basis of big data-driven analysis to determine structural evolution of organic electrtolyte at -30°C.
Dr. Yujun Xie is currently a postdoctoral fellow in the Department of Nuclear Engineering at UC Berkeley and the National Center for Electron Microscopy at Lawrence Berkeley National Lab under the supervised of Prof. Peter Hosemann and Dr. Peter Ercius. He received a B.S in Materials Science and Engineering from the Drexel University with highest honor and a Ph.D in Mechanical Engineering from Yale University. Under the supervised of Prof. Judy Cha and Prof. Jan Schroers, he applied in situ transmission electron microscopy to systematically study the solidification and crystal growth mechanism in non-equilibrium alloy systems at unprecedented temporal and spatial resolution. Dr. Xie continued his postdoctoral research focusing on developing four-dimensional scanning transmission electron microscopy (4D-STEM) techniques combining with big data processing methods to study the structural mechanics and the related microstructure evolution of structural alloy and organic materials under extreme environments. Dr. Xie has published 7 first author or co-first author papers in Nature Communication，Advanced Materials，Physical Review Letter. He was awarded 3 U.S. patents and is the recipient of MRS Gold Graduate Student Award, Ludo Frevel Crystallography Scholarship and Chinese government award for outstanding self-financed students abroad.