Correlations among stress corrosion cracking,grain-boundary microchemistry,and Zn content in high Zn-containing Al-Zn-Mg-Cu alloys  

高Zn含量Al-Zn-Mg-Cu合金中应力腐蚀开裂、晶界微化学成分及Zn含量之间的关系

作　　者：Ding-ling YUAN Song-yi CHEN Kang-hua CHEN Lan-ping HUANG Jiang-yu CHANG Liang ZHOU Yun-feng DING 袁丁玲;陈送义;陈康华;黄兰萍;昌江郁;周亮;丁云峰(中南大学轻合金研究院,长沙410083;中南大学有色金属先进结构材料与制造协同创新中心,长沙410083;中南大学轻质高强结构材料国家级科技重点实验室,长沙410083)

机构地区：[1]Light Alloy Research Institute,Central South University,Changsha 410083,China [2]Collaborative Innovation Center of Advanced Nonferrous Structural Materials and Manufacturing,Central South University,Changsha 410083,China [3]National Key Laboratory of Science and Technology for National Defence on High-Strength Lightweight Structural Materials,Central South University,Changsha 410083,China

出　　处：《Transactions of Nonferrous Metals Society of China》2021年第8期2220-2231,共12页中国有色金属学报（英文版）

基　　金：financial supports from the National Key Research and Development Program of China(No.2016-YFB0300801);the State Key Laboratory of High Performance Complex Manufacturing of Central South University,China(No.ZZYJKT2020-03);the National Key Laboratory of Science and Technology for National Defence on High-strength Lightweight Structural Materials of China(No.20190104)。

摘　　要：The correlations among the corrosion behaviour,grain-boundary microchemistry,and Zn content in Al-Zn-Mg-Cu alloys were studied using stress corrosion cracking(SCC)and intergranular corrosion(IGC)tests,combined with scanning electron microscopy(SEM)and high-angle angular dark field scanning transmission electron microscopy(HAADF-STEM)microstructural examinations.The results showed that the tensile strength enhancement of high Zn-containing Al-Zn-Mg-Cu alloys was mainly attributed to the high density nano-scale matrix precipitates.The SCC plateau velocity for the alloy with 11.0 wt.%Zn was about an order of magnitude greater than that of the alloy with 7.9 wt.%Zn,which was mainly associated with Zn enrichment in grain boundary precipitates and wide precipitates-free zones.The SCC mechanisms of different Zn-containing alloys were discussed based on fracture features,grain-boundary microchemistry,and electrochemical properties.通过应力腐蚀开裂测试、晶间腐蚀测试实验结合扫描电镜以及高角度环形暗场像扫描透射电镜观测,研究Al-Zn-Mg-Cu合金中腐蚀行为、晶界中微化学成分以及合金Zn含量之间的关系。结果表明,高Zn含量Al-Zn-Mg-Cu合金抗拉强度的提高主要归因于基体中形成的高密度纳米析出相。含11.0%Zn合金比含7.9%Zn(质量分数)合金的应力腐蚀平台速率高大约一个数量级,其主要原因是形成高Zn含量的晶界析出相和较宽的无沉淀析出带。基于合金的腐蚀断裂形貌、晶界微化学成分以及电化学性能,讨论不同Zn含量合金的应力腐蚀开裂机制。

关 键 词：Al-Zn-Mg-Cu alloy stress corrosion cracking Zn content grain-boundary microchemistry 

分 类 号：TG146.21[一般工业技术—材料科学与工程]