Lee Hsun Lecture Series

Topic: Microscopic Insights of Mechanical Behaviours from Neutron Diffraction Measurements

Speaker: Prof. Xun-Li Wang
　　　　Department of Physics, City University of Hong Kong

Microscopic Insights of Mechanical Behaviours from Neutron Diffraction Measurements

Xun-Li Wang
Department of Physics, City University of Hong Kong
83 Tat Chee Ave., Kowloon, Hong Kong

Abstract: Neutron scattering is a powerful method for characterizing the mechanical behaviours of materials.  In this talk, I will use several examples, from residual stress mapping in welds to in-situ loading studies of nanostructured and metallic glass alloys, to illustrate how this technique is used to gain microscopic insights of mechanical behaviours in engineering materials. We have recently applied in-situ neutron diffraction measurements to study deformation mechanisms in high entropy alloys at 10 K.  In contrast to room temperature, where the deformation is dominated by dislocation activities, at low temperatures, several other deformation mechanisms are also operating, which include stacking faults, twining, phase transformation, and serration.  Competitions between these different deformation mechanisms will be illustrated.  Finally, scientific opportunities at the new China Spallation Neutron Source will be discussed. 

Xun-Li Wang （王循理）
Chair Professor and Head
Department of Physics
City University of Hong Kong
83 Tat Chee Avenue
Kowloon, Hong Kong

In August 2012, Dr. Xun-Li Wang joined the City University of Hong Kong as a Chair Professor and Head of the Department of Physics and Materials Science. In July 2017, the department split and Professor Wang assumed the headship of the new Department of Physics.

Prior to coming to Hong Kong, he had been working at Oak Ridge National Laboratory in the US, rising through the ranks to Distinguished Staff Member. He was responsible for the design, construction, and early commission of VULCAN, a powerful engineering diffractometer at the Spallation Neutron Source, Oak Ridge National Laboratory.  As a senior scientist in the Neutron Science Directorate, he led innovative research, using neutron scattering as a primary tool, to understand deformation and phase transformation behavior in complex materials.  His current research interests include structure and dynamics in metallic glass, deformation behaviors in high entropy alloys, and magneto-elastic coupling in magnetic shape memory alloys.

Professor Wang received his Ph.D. from Iowa State University and B.S. from Peking University, both in Physics. He is an elected Fellow of the American Physical Society (APS), and American Association for the Advancement of Science (AAAS).  His early work on welding residual stresses was awarded an A. F. Davis Medal by the American Welding Society.  He served as Chair of the inaugural Gordon Research Conference on Neutron Scattering.