Cu含量对Al-9.0Zn-1.5Mg-xCu合金断裂韧性的影响  

Effect of Cu content on fracture toughness of Al-9.0Zn-1.5Mg-xCu alloys

作　　者：韦卫昌 马志民[3] 张梦晗 刘胜胆[1,2,4] 叶凌英[1,2] 程全士 WEI Wei-chang;MA Zhi-min;ZHANG Meng-han;LIU Sheng-dan;YE Ling-ying;CHENG Quan-shi(School of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Non-ferrous Metals Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China;Baotou Vocational&Technical College,Baotou 014030,China;National Key Laboratory of Light and High Strength Structural Materials,Central South University,Changsha 410083,China;Henan Key Laboratory of Fastening Connection Technology,Xinyang 464000,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]中南大学有色金属材料科学与工程教育部重点实验室,长沙410083 [3]包头职业技术学院,包头014030 [4]中南大学轻质高强结构材料国家重点实验室,长沙410083 [5]河南省紧固连接技术重点实验室,信阳464000

出　　处：《中国有色金属学报》2022年第11期3245-3256,共12页The Chinese Journal of Nonferrous Metals

基　　金：河南省紧固连接技术重点实验室开放课题(JGLJ2103);国家重点研发计划资助项目(2016YFB0300901)

摘　　要：采用Kahn撕裂实验,结合金相、扫描电镜、扫描透射电镜、数字图像相关法和电子背散射衍射等手段,研究了Cu含量对Al-9.0Zn-1.5Mg-x Cu合金断裂韧性的影响规律。结果表明:随着Cu含量从0%增大到2.6%(质量分数),合金断裂韧性先逐渐增大,在Cu含量为1.0%~1.3%时达到最高值,而后大幅减小。随着Cu含量从0%增大到1.0%~1.3%,合金的再结晶晶粒面积分数逐渐增大,导致裂纹形核过程的变形量和穿过再结晶晶粒扩展的比例增大;裂纹单位面积形核功(UIE)和单位面积扩展功(UPE)逐渐增大。Cu含量为2.6%时,合金残余第二相的面积分数、晶界上部分η相的尺寸增大,导致裂纹形核过程的变形量减小;η′强化相的间距减小,导致晶内-晶界强度差和裂纹沿再结晶晶界扩展的比例明显增大;UIE和UPE均大幅减小。The effect of Cu content on the fracture toughness of Al-9.0Zn-1.5Mg-xCu alloys was investigated by means of Kahn-tear test,optical microscopy(OM),scanning electron microscopy(SEM),scanning transmission electron microscopy(STEM),digital image correlation(DIC),and electron backscattered diffractionometry(EBSD).With the increase of Cu content from 0%to 2.6%(mass fraction),the fracture toughness of alloys first increases,reaching the maximum value at 1.0%−1.3%,and then decreases greatly.With the increase of Cu content from 0%to 1.0%−1.3%,the area fraction of recrystallized grains increases gradually,leading to an increase in the deformation amount during crack initiation and the proportion of transgranular fracture;therefore,unit initiation energy(UIE)and unit propagation energy(UPE)increase gradually.When Cu content is 2.6%,the area fraction of residual phase increases and there are some largeηphase particles at grain boundaries,leading to a decrease in deformation amount during crack initiation;the spacing ofη′strengthening precipitates decreases,leading to an increase in the strength difference between the grain interior and the grain boundary and therefore higher proportion of intergranular fracture.As a result,UIE and UPE decrease greatly.

关 键 词：AL-ZN-MG-CU合金 CU含量 断裂韧性 裂纹形核功 裂纹扩展功 

分 类 号：TG146.2[一般工业技术—材料科学与工程]