清华大学材料科学与工程研究院《材料科学论坛》学术报告
报告时间：2025年9月19日上午10:00-11:30
报告人：Prof. Yanjun Li（Norwegian University of Science and Technology）
报告地点：清华大学逸夫技术科学楼A205学术报告厅
邀请人：于荣老师
报告题目：Solute clustering and early-stage precipitation in Al-Mg-Si alloys
报告简介：
With high specific strength, AA6xxx Al-Mg-Si alloys are widely applied in automotive industry. Their high strength is achieved by age hardening. In many of the alloys, high density small solute clusters (0.5–1 nm) can form during long-time room temperature storage (i.e. natural aging, NA) between solution treatment and artificial aging (AA), which severely slow down the age-hardening response and lower the achievable peak-aged strength. This work studied the influences of NA up to 1 year on the AA responses of a dilute 6060 alloy and a concentrated 6082 alloy. We demonstrate that NA has a strong negative effect on the age-hardening response during AA of 6082 alloy, while NA has positive effects on AA of 6060 alloy. To understand the mechanism lying behind, we examined the atomic structures of solute clusters and GP zones formed during NA using atomic-resolution transmission electron microscopy (TEM) and atom probe tomography (APT). It is found that the negative or positive effective effects of NA are dependent of the type of GP zones formed in the alloys, where multiple b”-eye type GP zones are crucial for the formation of age hardening phase, b” precipitates. Taking advantage of the mechanism, we designed a pre-aging treatment to reverse the negative NA effect in 6082 alloy, achieving higher strength and ductility by using a shorter AA time than normal AA treatment without NA.
报告人简介：
Yanjun Li is Professor of Physical Metallurgy, at Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU). He is currently Scientific Director of Norwegian Laboratory of Mineral and Materials Characterization (MiMaC). He obtained his Ph.D in 1997 from Harbin Institute of Technology. He had worked as Research Metallurgist at Hydro Aluminium, and Senior Research Scientist at Group of Materials Physics, SINTEF M&K before he joined NTNU as a full professor in 2013. In 2019, he worked as a Visiting Professor at the Massachusetts Institute of Technology (MIT) for 6 months, doing teaching and joint research. He was elected as a member of Norwegian Academy of Technological Science (NTVA) in 2020. His research field includes Solidification and casting, Solid state phase transformation, Deformation and recrystallization, Advanced materials characterization and Multiscale materials calculation and microstructure modeling. So far, he has published more than 180 international scientific journal articles.