热暴露对欠时效态Al-Cu-Mg-Ag合金拉伸性能的影响  

Effect of thermal exposure on tensile properties of underaged Al-Cu-Mg-Ag alloy

作　　者：夏卿坤[1,2,3] 刘志义[2,3] 李云涛[2,3] 马飞跃[2,3] 柏松[2,3] 

机构地区：[1]长沙学院机电工程系,长沙410003 [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]中南大学材料科学与工程学院,长沙410083

出　　处：《中国有色金属学报》2009年第5期808-815,共8页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展计划资助项目(2005CB623705-04)

摘　　要：采用拉伸力学性能测试、透射电镜微观组织分析和扫描电镜断口分析等方法，研究热暴露对一种欠时效态Al—Cu-Mg-Ag合金力学性能及微观组织的影响。结果表明：在150℃热暴露下，欠时效态Al-Cu-Mg-Ag合金的剩余强度先上升后下降，强度峰值出现在100h；热暴露1000h后，合金的力学性能相对欠时效态合金的无明显下降；在200～300℃热暴露时，合金强度随时间的延长而下降，伸长率随着时间的延长而增大；在300℃热暴露时，强度明显下降，热暴露10h后，其抗拉强度只有272．5MPa，暴露100h后，其抗拉强度降至114．5MPa；欠时效态合金细小分布的Ω相随着热暴露温度的升高，Ω相长大并粗化，θ’相析出，无沉淀析出带（PFZ）变宽；在250℃下热暴露时，Ω相明显粗化且数量稀少；合金中的Ω相和θ’相在300℃热暴露100h后，均转变成平衡Ω相。The effects of long term thermal exposure on mechanical properties and microstructures of an underaged Al-Cu-Mg-Ag alloy were investigated by tensile test, transmission electron microscopy （TEM） and scanning electron microscopy （SEM）. The results show that the residual strength of underaged samples appears to increase first whereas then decrease, the peaking strength is obtained after exposuring at 150 ℃ for 100 h. Compared with the underage condition, the mechanical properties of the underaged Al-Cu-Mg-Al alloys have no obvious variation after exposuring for 1 000 h, which represent superior heat resistance. The residual strengths of underage samples decrease versus elongation increases as the exposure time prolongs and temperature rises from 200 to 300 ℃. The tensile strengths of the samples are 272.5 MPa and 114.5 MPa after exposuring at 300 ℃ for 10 h and 100 h, respectively, revealing obvious reduce in strength. With increasing exposure temperature and/or time, the thickening kinetics of Ω phase greatly increases and the precipitation free zones are broadened at grain boundary. Finally, Ω and θ＇ phases are replaced by equilibrium θ phase, which decreases the strength of the alloy.

关 键 词：Al-Cu—Mg—Ag合金 欠时效 热暴露 力学性能 显微组织 

分 类 号：TG146[一般工业技术—材料科学与工程]