NERS Colloquium: Qing Peng, NERS
WHEN: November 16, 2018 4:00 pm-5:00 pm
Qing Peng, NERS
Mystery of the Formation of <100> Loops in Irradiated Iron
Host: Fei Gao
Abstract: Dislocations are one-dimensional defects and play an essential role in properties of crystalline, including bcc iron. The <100> interstitial-type dislocation loops commonly exist in irradiated ferritic steels as discovered by Transmission Electronic Microscopy studies since early 1960s. The formation mechanism, however, is still a puzzle despite extensive investigations and debates in the past half-century. It is well accepted that the formation energies for <100> interstitial loops are higher than that of <111> interstitial loops. As a consequence, the <100> interstitial loops are unlikely to form since it is energetically unfavorable. The direct observations of the formation of <100> interstitial loops are therefore absent. Part of the reason is that the generation of these loops are too short for experiments, but also thought to be too long for atomistic simulations. Using large scale molecular dynamics simulations with up to 220 million atoms, we directly observed the dynamical process of the generation of the <100> interstitial loops in a single displacement cascade event. The formation mechanism of these loops will be further discussed.
Bio: Dr. Qing Peng is a Research Fellow in the department of Nuclear Engineering and Radiological Sciences, University of Michigan-Ann Arbor. He received his Ph.D. in Physics from University of Connecticut in 2005, M.S. from Physics department, State University of New York at Binghamton in 2000, and B.S. in Nuclear Engineering from Peking University in 1998. His current research focuses on computational modeling of the irradiation damage of materials using molecular dynamics simulations, first-principles calculations, and multiscale modeling. Dr. Peng has published over 80 peer-reviewed journal papers with H-index of 23. Dr. Peng serves as an Editorial board member for Scientific Reports since 2015.