A hidden precipitation scenario of theθ’-phase in Al-Cu alloys

作     者：L.Zhou C.L.Wu P.Xie F.J.Niu W.Q.Ming K.Du J.H.Chen L.Zhou;C.L.Wu;P.Xie;F.J.Niu;W.Q.Ming;K.Du;J.H.Chen

作者机构：center for high-resolution electron microscopycollege of materials science and engineeringhunan universitychangshahunan410082china shenyang national laboratory for materials scienceinstitute of metal researchchinese academy of sciences.shenyan7.110016china 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2021年第75卷第16期

页      面：126-138页

核心收录：

学科分类：0806[工学-冶金工程] 0817[工学-化学工程与技术] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0802[工学-机械工程] 0702[理学-物理学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the National Natural Science Foundation of China(Nos.51831004,51801060,51671082,11427806,51471067) the National Key Research and Development Program of China(No.2016YFB0300801) 

主　　题：AlCu alloy Age-hardening Precipitation Electron microscopy 

摘      要：Al-Cu binary alloys are important and interesting industry *** to date,the formation mechanisms of the key strengthening precipitates,namedθ’-phase,in the alloys are still ***,we report that for non-deformed bulk Al-Cu alloys theθ’-phase actually has its own direct precursors that can form only at elevated aging temperature(ca.200℃).These high-temperature precursors have the same plate-like morphology as theθ’-phase precipitates but rather different *** imaging reveals that they have a tetragonal structure with a=0.405 nm and c=1.213 nm,and an average composition of Al_(5-x)Cu_(1+x)(0≤x1),being fully coherent with the *** precursor phase may initiate with a composition of Al5 Cu and evolve locally towards Al_(4)Cu_(2)in composition,eventually leading to a consequent structural transformation into theθ’-phase(Al4 Cu2=Al2 Cu).There are evidences that because of their genetic links in structure,such a high-temperature precursor may transform to theθ’-phase without having to change their morphology and interface *** study reveals a well-defined and previously hidden precipitation scenario for theθ’-phase to form in Al-Cu alloys at an elevated aging temperature.