报告平台：腾讯会议 ID:177 901 454、密码: 0615
报 告 人：Yucheng Liu 教授
工作单位：South Dakota State University
Metastable γ” (D022-Ni3Nb) particles are strengthening precipitates for commercial Inconel 625 Ni-based superalloy. Understanding their morphological evolution is critical for evaluating its hardening effects and guiding heat treatments to improve its yield strength. Here we present a phase-field model to model and analyze the nucleation and growth kinetics of metastable γ” in Inconel 625 during isothermal and non-isothermal aging conditions with thermodynamic properties, diffusion coefficients, and misfit strain data from both the literature and calibration to experimental results. We implemented the classical nucleation theory to introduce local nucleation taking into account local supersaturation. The simulated mean particle length and aspect ratio are in agreement with experimental data at 600 ℃ and 650 ℃ during isothermal aging. Utilizing the phase-field simulation results as input parameters, the coherency strengthening effect of γ” as a function of aging temperature and time is predicted. A multistage aging strategy to optimize the γ” strengthening effect and to reduce aging times using the developed phase-field model and coherency strengthening model is suggested.
Dr. Yucheng Liu (PhD, PE, FASME, FSAE) currently serves as the Department Head of Mechanical Engineering (ME) Department at South Dakota State University (SDSU) and holds the Duane Sander Professor of Entrepreneurial Engineering in the Jerome J. Lohr College of Engineering at SDSU. Prior to joining SDSU in the fall of 2021, Dr. Liu was Associate/Full Professor in the ME Department at Mississippi State University (MSU) since the fall of 2014. In that department, he served as Graduate Coordinator from 2016 to 2021 and held the Jack Hatcher Chair in Engineering Entrepreneurship in the Bagley College of Engineering from 2018 to 2021. Before joining MSU, Dr. Liu was Assistant Professor of the ME Department at the University of Louisiana at Lafayette (UL Lafayette). Dr. Liu received his PhD degree from the University of Louisville in 2005 and bachelor’s degree from the Hefei University of Technology in 1997, both in Mechanical Engineering. Dr. Liu’s research has historically focused on the areas of multiscale material modeling and simulation, high strain rate performance of materials, vehicle systems design and analysis, and hydropower and wave energy technology. His current research interests and activities center on gaining a better understanding of the process-structure-property-performance relations of structural materials through advanced multiscale theoretical framework and integrated computational and experimental methods. To date, Dr. Liu has published over 240 peer reviewed publications, including more than 130 peer reviewed journal articles, and received 2 patents. He has secured and managed over 40 grants totaling more than $15.5 million in extramural funding from a myriad of private, state, and federal agencies. Dr. Liu has served on review panels for many NSF, DOD, NASA, and DOE programs. Since becoming a faculty member in 2009, Dr. Liu has earned university, national, and international accolades for his outstanding contributions in research, teaching, and service. He received the Junior Faculty Researcher of the Year of the College of Engineering at UL Lafayette in 2013, the Outstanding Senior Faculty Research Award from the ME Department in 2016, MSU and BCOE Faculty Research Award in 2018, and the BCOE Service Award in 2021. Dr. Liu was named to the Jack Hatcher Chair in Engineering Entrepreneurship in 2018 and promoted to Full Professor in 2019. In his professional societies, Dr. Liu was elected a Fellow of ASME in 2017, a Fellow of SAE in 2019, and received the SAE Forest R. McFarland Award in 2020. Dr. Liu is a Professional Engineer registered in Ohio State and also holds active membership in ASEE and AAAS.