Dr. Yanfei Gao
Seminar Information
Solid-sate-bonding techniques have been widely used and investigated in welding and joining community, and also recently in novel nanomanufacturing processes. Nevertheless, it is well known in the community of mechanics of materials that crack healing, an opposite process to Griffith fracture, does not usually take place at ambient conditions except for extremely flat surfaces. Traditionally, the solid-state-bonding mechanisms are believed to be dominated by atomic interdiffusion across the interface. In contrary, we propose that both lateral diffusion along the interface and creep deformation of surrounding materials dominate the gap closure and thus dictate the kinetics of bonding. Additionally, the competition between these two processes defines a length scale, on which various solid-state-bonding techniques find their characteristic parametric space. Our model has been applied to friction stir welding and related techniques, where an additional technical hurdle on the interface stick-slip behavior has been solved.
Prof. Yanfei Gao joined the Department of Materials Science and Engineering, The University of Tennessee, Knoxville, in 2005. Prior to that, he obtained his BS in Engineering Mechanics and a dual BS in Computer Science from Tsinghua University in 1999, and PhD in Mechanical and Aerospace Engineering from Princeton University in 2003, followed by a two-year post-doc training at Brown University in 2003-2005. He was also a Joint Faculty with Oak Ridge National Laboratory in 2005-2018. His research activities focus on mechanics of materials, especially the deformation and failure mechanisms at extreme conditions. He has published 180 journals with many in in Acta Materialia and Journal of the Mechanics and Physics of Solids. He belongs to the 2% world top scientists from a Stanford University study and has more than 10,000 Google Scholar citations with an H-index of 49. He’s currently the Interim Director of Energy Science and Engineering Program, University of Tennessee & Oak Ridge Innovation Institute, and also the Site Director of NSF I/UCRC on Manufacturing and Materials Joining Innovation Center. In Fall 2023, he’s on leave at University of California, Riverside. For more information, please see: https://gao.utk.edu