Achieving highest Young’s modulus in Al-Li by tracing the size and bonding evolution of Li-rich precipitates  

作　　者：Chengpeng Xue Yuxuan Zhang Shuo Wang Guangyuan Tian Xinghai Yang Yubin Ke Zhenhua Xie Junsheng Wang 

机构地区：[1]School of Materials Science and Engineering,Beijing Institute of Technology,Beijing 100081,China [2]China Spallation Neutron Source,Dongguan Branch,Institute of High Energy Physics,Chinese Academy of Sciences,Dongguan 523803,China [3]Advanced Research Institute of Multidisciplinary Science,Beijing Institute of Technology,Beijing 100081,China

出　　处：《Journal of Materials Science & Technology》2023年第14期125-135,共11页材料科学技术（英文版）

基　　金：This work is financially supported by the National Natural Science Foundation of China(No.52073030).

摘　　要：For decades,it has been well accepted that every 1 wt.%Li addition to Al will reduce Al alloy’s density by 3%and increase its Young’s modulus by 6%.However,the fundamental mechanism of modulus improve-ments stays controversial though all studies agreed that the contribution of such a substantial boosting comes from Li-rich clusters either in solid solution or precipitations.In this study,we experimentally produce nano-sized Li-rich clusters by non-equilibrium solidification using centrifugal casting and trace their evolutions as a function of subsequent heat treatments.High-resolution transmission electron mi-croscopy(HRTEM)reveals a further decrease in the lattice constants of Li-rich regions from the as-cast(0.406 nm),solid solution(0.405 nm)to the aged state(0.401 nm),while Young’s modulus of the Al-Li al-loy reaches 89.16 GPa.Small-angle neutron scattering(SANS)experiments and first-principle calculations based on density functional theory have shown both the bond strength around precipitates and the size of those Li-rich region dominate Young’s modulus.At the beginning,it is volumetric compression due to Li addition that increases modulus,tightening the Al-Al potential curves.In the end,it is the Al-Al and Al-Li valence bonds in Al 3 Li at large size and high-volume fraction which increase its second derivative of internal energy and thus Young’s modulus.

关 键 词：Al-Li alloy Young’s modulus SANS HRTEM DFT Precipitate kinetics 

分 类 号：U465.11[一般工业技术—材料科学与工程] TG142[机械工程—车辆工程]