淬火速率对含Sc(Zr)高强韧Al-Zn-Mg-Cu合金微观组织和力学性能的影响  

Effects of quench rate on mechanical properties and microstructures of high strength and toughness Al-Zn-Mg-Cu alloy with Sc(Zr)addition

作　　者：李芳芳[1] 徐国富[1,2] 李耀 黄继武[1,2] 邓英[1,2] 尹志民 LI Fang-fang;XU Guo-fu;LI Yao;HUANG Ji-wu;DENG Ying;YIN Zhi-min(School of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous Metal Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,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

出　　处：《中国有色金属学报》2020年第2期264-272,共9页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51601229);广东省科学研究计划项目(2016B090931004);中南大学贵重精密仪器开放共享基金(CSUZC201812)。

摘　　要：通过末端淬火实验(JEQ)、X射线衍射仪(XRD)、扫描电镜(SEM)、透射电子显微镜(TEM)研究一种热挤压Al-Zn-Mg-Cu-Sc-Zr棒材的淬火敏感性。结果表明:随着距离淬火端越远,冷却速率从1800℃/min下降至111℃/min,合金硬度从150 HB下降至133 HB,抗拉强度从430 MPa下降至375 MPa。当冷却速率为131.2℃/min时,合金的硬度为135 HB,合金淬透深度约为93mm。随着冷却速率的降低,端淬时远离淬火端位置,平衡η相先后在晶界、晶内处析出、长大、粗化;时效后,析出的η′强化相的数量减小;时效后,合金内出现无沉淀析出带(PFZ),晶界的PFZ变宽,宽化至160 nm。The quench sensitivity of the Al-7.01Zn-1.39Mg-2.25Cu-0.07Zr-0.07Sc alloy were investigated by the Jominy end-quench(JEQ)test,X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that,with the increase of the distance from the quenched end of the bar(d)and the decrease of average cooling rates from 1800℃/min to 111℃/min,the hardness falls to 133 HB from 150 HB and the tensile strength falls to 375 MPa from 430 MPa.When the critical average cooling rate is about 131.2℃/min and the d is 93 mm,90%of the maximum hardness can be obtained.As the cooling rate reduces,the microstructure change as follows:theηequilibrium phase forms in the grain boundary and grained at different positions from the quenching end in the JEQ process in sequence,the number ofη′strengthening precipitates decreases after aging,the width of precipitate free zone near grain boundaries reaches up to 160 nm.

关 键 词：Al-Zn-Mg-Cu-Sc-Zr合金 淬火敏感性 力学性能 显微组织 

分 类 号：TG146.2[一般工业技术—材料科学与工程]