Abstract：
Medium and high entropy alloys (MEA/HEA) have attracted a great amount of attentions during the last decade due to their unusual but desired mechanical properties, such as an increase in both strength and ductility with decreasing temperature exhibited by the FeNiCoCr alloys. The alloy compositions of MEA/HEAs are substantially higher than that of the dilute-limit alloys and are considered as concentrated alloys. The mechanical behaviors of these alloys are sometimes fundamentally different from the dilute-limit alloys and requires mechanistic understanding for alloys design. In this talk, the computational challenges and opportunities of revealing fundamental deformation mechanisms in these concentrated alloys using multiple techniques, including density functional theory, molecular dynamics, and kinetic Monte Carlo, will be overviewed. The effects of alloy element on complex electronic and magnetic structure of the materials will be discussed. Particularly, we will focus on model alloys (e.g. Fe-Cr and Fe-Ni) in which the effects can be discerned. In addition, the influence of local atomistic configurations and compositional effects on elastic properties and ideal shear strength of these alloys will be examined. The time scale challenges of conventional molecular dynamics and potential usage of Self-Evolving Atomistic Kinetic Monte Carlo to overcome such difficulty will be discussed.   These insights may contribute to the development of next-generation structural alloys for various energy
applications.
 
Biography of Dr. Haixuan Xu
Dr. Haixuan Xu is Assistant Professor of Materials Science and Engineering at University of Tennessee. Before he moved to UT in 2013, he was a postdoctoral research fellow in Oak Ridge National Laboratory (ORNL). He received his B.S. degree in Metallic Materials Engineering from Dalian University of Technology (China) in 2005, M.S. degree in Materials Science and Engineering from University of Florida in 2007, and Ph.D. degree in Materials Science and Engineering from University of Florida in 2010. His research interests include defect evolution and interaction, radiation effects in materials, magnetism in 2D materials, flexoelectric effects and electromagnetic coupling, long-time atomistic simulations, oxide superlattices, heterostructures, structural alloys, high entropy alloys, on-the-fly kinetic Monte Carlo. He has published about 40 papers in peer-reviewed journal including PRL and PNAS. He has delivered more than 30 invited and oral presentations in international conferences.