双级时效对铸造Al-Si-Mg-Cu合金微观组织和力学性能的影响  

Effect of Dual Aging on Microstructure and Mechanical Properties of As-cast Al-Si-Mg-Cu Alloy

作　　者：朱聪聪 何家威 耿汝伟 董瑞煌 高文理[2] ZHU Congcong;HE Jiawei;GENG Ruwei;DONG Ruihuang;GAO Wenli(School of Mechanical and Electrical Engineering,China University of Mining and Technology,Xuzhou 221116,China;College of Materials Science and Engineering,Hunan University,Changsha 410082,China)

机构地区：[1]中国矿业大学机电工程学院,江苏徐州221116 [2]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《湖南大学学报(自然科学版)》2025年第4期186-194,共9页Journal of Hunan University:Natural Sciences

基　　金：中央高校基本科研业务费(2024QN11016);国家自然科学基金资助项目(52374386)。

摘　　要：采用扫描电镜、透射电镜和室温拉伸测试研究了双级时效工艺对铸造Al-Si-MgCu合金微观组织和力学性能的影响.本研究采用的双级时效制度是低温预时效和高温终时效.结果表明:合金在低温预时效阶段会形成更多析出形核点,经高温终时效后,合金中析出更多的θ′′相并有β′′相析出.当预时效制度为155℃/8 h时,随着终时效温度的升高,合金内θ′′相的尺寸逐渐增大,β′′相形貌变化并不明显,合金的抗拉强度随着终时效温度的升高呈先上升后下降的趋势,合金的延伸率随着终时效温度的升高呈显著下降的趋势,165℃为合金较好的终时效温度;当双级时效制度为155℃/x h+165℃/2 h时,随着预时效时间的增加,合金中θ′′相和β′′相的数量逐渐增多;当双级时效制度为155℃/8 h+165℃/x h时,随着终时效时间的增加,θ′′相的尺寸呈逐渐增大的趋势,在终时效时间为8 h之前,合金中β′′相的数量和尺寸并没有明显变化,继续延长终时效时间β′′相也开始长大.通过优化双级时效工艺,可实现θ′′相与β′′相的双析出相强化,经过155℃/8 h+165℃/2 h双级时效后的抗拉强度最高可达380 MPa,经过155℃/8 h+165℃/8 h双级时效后的断后延伸率提高至3.4%.The effects of dual aging process on microstructure and mechanical properties of as-cast Al-Si-Mg-Cu alloy were investigated by scanning electron microscopy,transmission electron microscopy and tensile test at room temperature.The dual aging process used in this study was low temperature pre-aging and high temperature final aging.The results showed that more precipitation nucleation sites were formed in the low temperature pre-aging stage of the alloys.After high temperature final aging,moreθ"phases and someβ"phases were precipitated in the alloys.When the pre-aging was 155°C/8 h,the size ofθ"phase gradually increased with the increase of final aging temperatures,while the morphology of theβ"phase did not change significantly.The tensile strength of the alloys increased first and then decreased with the increase of the final aging temperatures.The elongation of the alloys decreased significantly with the increase of the final aging temperature,and 165°C was the better final aging temperature of the alloy.When the dual aging process was 155°C/x h+165°C/2 h,the number ofθ"phase andβ"phase in the alloy gradually increased with the increase of pre-aging time.When the dual aging process was 155°C/8 h+165°C/x h,the size ofθ"phase increased gradually with the increase of the final aging time.The number and size ofβ"phase in the alloy did not change significantly before the final aging time was 8 h.Continuing to extende the final aging time,theβ"phase also began to grow.The dual precipitated phase strengthening ofθ"phase andβ"phase can be realized by optimizing the dual aging process.The tensile strength of the alloy can reach 380 MPa after 155°C/8 h+165°C/2 h dual aging,while the elongation of the alloy was increased to 3.4%after 155°C/8 h+165°C/8 h dual aging.

关 键 词：铸造Al-Si-Mg-Cu合金 双级时效 析出相 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]