Complex Precipitation Sequences of Al-Cu-Li-(Mg)Alloys Characterized in Relation to Thermal Ageing Processes  

作　　者：Zhen Gao Jiang-Hua Chen Shi-Yun Duan Xiu-Bo Yang Cui-Lan Wu 

机构地区：[1]Center for High-Resolution Electron Microscopy,College of Materials Science and Engineering,Hunan University

出　　处：《Acta Metallurgica Sinica(English Letters)》2016年第1期94-103,共10页金属学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51371081, 11427806,51471067,51501059 and 51171063);the National Basic Research Program of China(No.2009CB623704)

摘　　要：The A1-Cu-Li-（Mg） alloy is a high-performance lightweight material strengthened by complex coexisting precipitates that form in the alloy upon thermal ageing. Using high-resolution （scanning） transmission electron microscopy in association with first-principles energy calculations, we systematically studied the complex coexisting precipitates in the alloys and correlated their precipitation sequences with thermal ageing processes applied. The principal results are the following： （1） eight types of precipitates can be observed in the alloy; （2） of these precipitates, the Tl-phase is most stable. The S-phase precipitates with segregated Li atoms at their interfacial edges are unexpectedly more stable than the a-phase; （3） the Tl-phase has a characteristic precursor that plays the key role in its nucleation and growth.The A1-Cu-Li-（Mg） alloy is a high-performance lightweight material strengthened by complex coexisting precipitates that form in the alloy upon thermal ageing. Using high-resolution （scanning） transmission electron microscopy in association with first-principles energy calculations, we systematically studied the complex coexisting precipitates in the alloys and correlated their precipitation sequences with thermal ageing processes applied. The principal results are the following： （1） eight types of precipitates can be observed in the alloy; （2） of these precipitates, the Tl-phase is most stable. The S-phase precipitates with segregated Li atoms at their interfacial edges are unexpectedly more stable than the a-phase; （3） the Tl-phase has a characteristic precursor that plays the key role in its nucleation and growth.

关 键 词：AI-Cu-Li alloy Electron microscopy Ageing PRECIPITATION STRENGTH 

分 类 号：TG146.21[一般工业技术—材料科学与工程]