Relationship Between the Strengthening Effect and the Morphology of Precipitates in Al–7.4Zn–1.7Mg–2.0Cu Alloy  

作　　者：Xiubo Yang Jizi Liu Jianghua Chen Caiyun Wan Lei Fang Ping Liu Cuilan Wu 

机构地区：[1]College of Materials Science & Engineering, Hunan University [2]Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University

出　　处：《Acta Metallurgica Sinica(English Letters)》2014年第6期1070-1077,共8页金属学报（英文版）

基　　金：financially supported by the National Basic Research Program of China (No. 2009CB623704);the National Natural Science Foundation of China (Nos. 51171063, 10904034, 51071064 and 51301064);Instrumental Innovation Foundation of Hunan Province (No. 2011TT1003);the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province and the Aid Program for Young Teachers (No. 531107040548)

摘　　要：The morphological evolution of the precipitates in Al–7.4Zn–1.7Mg–2.0Cu（wt%） alloy was studied by highresolution transmission electron microscopy（HRTEM）. Statistics reveal that the hardness of the alloy changes accordingly with the change of the average thickness–diameter ratio of precipitates. The GPII zones are mainly responsible for the first and also the highest hardness peak. They grow in diameter and keep 7-atomic-layer in thickness. Once the thickness changes, the phase transformation from GPII zone to g0 or g-precursor would occur. The resultant metastable g0 and g-precursor precipitates grow in both diameter and thickness, but much faster in the former. After the first hardness peak,the metastable g0 precipitates and g-precursor, coexisting with part of GPII zones, are counted as the main hardening precipitates.The morphological evolution of the precipitates in Al–7.4Zn–1.7Mg–2.0Cu（wt%） alloy was studied by highresolution transmission electron microscopy（HRTEM）. Statistics reveal that the hardness of the alloy changes accordingly with the change of the average thickness–diameter ratio of precipitates. The GPII zones are mainly responsible for the first and also the highest hardness peak. They grow in diameter and keep 7-atomic-layer in thickness. Once the thickness changes, the phase transformation from GPII zone to g0 or g-precursor would occur. The resultant metastable g0 and g-precursor precipitates grow in both diameter and thickness, but much faster in the former. After the first hardness peak,the metastable g0 precipitates and g-precursor, coexisting with part of GPII zones, are counted as the main hardening precipitates.

关 键 词：Aluminum alloys Precipitates Age hardening Electron microscopy Morphology 

分 类 号：TG146.21[一般工业技术—材料科学与工程]