Influence of quench-induced precipitation on aging behavior of Al-Zn-Mg-Cu alloy  

淬火析出对Al-Zn-Mg-Cu合金时效行为的影响(英文)

作　　者：唐建国[1] 陈慧[1] 张新明[1] 刘胜胆[1] 刘文军[1] 欧阳惠[1] 李红萍[2] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]上海飞机设计研究院,上海200232

出　　处：《Transactions of Nonferrous Metals Society of China》2012年第6期1255-1263,共9页中国有色金属学报（英文版）

基　　金：Project (201012200238) supported by the Freedom Inquiry Program of Central South University,China;Project (2012CB61950) supported by the National Basic Research Program of China

摘　　要：The effects of quenching and aging （T6, T7 and RRA） on the microstructural evolution of an A1-Zn-Mg-Cu alloy were investigated by hardness test, optical microscopy （OM）, transmission electron microscopy （TEM） and differential scanning calorimetry （DSC） measurements. It is found that the hardness of T6 aged sample after water-quenching is the highest. The quench sensitivities of T7 and RRA are almost the same, which are 1.2% higher than that of T6. TEM observation shows that the quench sensitivity for the studied alloy is mainly caused by heterogeneous precipitation during slow quenching. Many r/phases precipitate on A13Zr dispersoids inside recrystallized grains and at （sub） grain boundaries, while T and S phases form in the substructure with high density of dislocations and defects. After aging, the η＇ precipitates are coarser in the vicinity of equilibrium r/phase. However, the size and morphology of the precipitates show different characteristics among T6, T7 and RRA treatments. The DSC results are highly consistent with the TEM observation. The DSC curves of T6 aged samples are different from those of T7 and RRA aged samples, which also reflects the differences on the microstructure.采用硬度测试、光学显微镜(OM)、透射电镜(TEM)和差示扫描量热法(DSC)研究淬火和时效(T6、T7、RRA)对Al-Zn-Mg-Cu合金微观组织的影响。研究发现水淬合金经T6时效后的硬度最高。T7和RRA时效后样品的淬火敏感性相当,较T6时效的高1.2%。TEM观察表明,合金的淬火敏感性主要是由缓慢冷却时非均匀析出引起的。大量η相在再结晶晶粒内的Al3Zr弥散粒子和(亚)晶界上形核,而S和T相在有高密度位错和缺陷的亚结构区生成。时效后,平衡η相周围的η'相更加粗大。经T6、T7、RRA处理后,这些析出相的尺寸和形貌呈现出不同的特征。DSC结果与TEM观察结果一致。T6态的DSC曲线和T7、RRA态的不同,反映了不同的微观组织。

关 键 词：Al-Zn-Mg-Cu alloy QUENCHING quench sensitivity aging PRECIPITATION 

分 类 号：TG156.92[金属学及工艺—热处理]