Microstructure and mechanical properties of cast Al-Li-Mg alloy:Role of Cu addition and heat treatment  

作　　者：Fangzhou Qi Guohua Wu Liang Zhang Xin Tong Xuanxi Xu Youjie Guo 

机构地区：[1]National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Journal of Materials Science & Technology》2024年第32期1-16,共16页材料科学技术(英文版)

基　　金：supported by the National Natural Science Foundation of China(Nos.51871148 and 51821001).

摘　　要：In this work,the effect of Cu addition and heat treatment schemes on the microstructural evolution,mechanical properties,and corresponding strengthening mechanism of cast Al-Li-Mg alloy were investi-gated.Results indicate that the dendritic segregation would be induced after the introduction of Cu,and a well-designed two-stage solution treatment could effectively dissolve secondary phases.With Cu addi-tion,aging hardening responses of the alloys were accelerated,accompanied by a continuous increase in the volume fraction of both S’-Al_(2) CuMg and Al_(3) Li phases,which enhanced the precipitation strengthen-ing effect.Furthermore,in Cu-containing alloys,both the coarsening of Al_(3) Li phases and the expansion of Al3 Li-precipitation free zones(PFZ)were inhibited during the aging process.However,severe strain accumulation was found at the interface between the coalesced S’phase andα-Al matrix,which reduced the ductility of the alloy.A good combination of strength and ductility(YS=308 MPa,UTS=428 MPa,EL=5.0%)was obtained in the Al-2.5Li-2Mg-1Cu-0.12Zr alloy aged at 175°C for 32 h due to the nar-rowed Al3 Li-PFZ and the synergistic strengthening of Al3 Li and S’phase.This work is expected to provide guidelines for designing novel cast Al-Li alloys with wider applications.

关 键 词：Cast Al-Li alloy Cu addition Heat treatment Al_(3)Li Al_(2)CuMg Strength mechanisms 

分 类 号：TG1[金属学及工艺—金属学]