Al-Zn-Mg-Cu-Zr-0.12Ce合金铸锭的均匀化退火及组织演变
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摘要
采用光学显微镜(OM)、扫描电镜(SEM)、电子探针(EPMA)、波谱分析(WDS)、X射线衍射(XRD)以及差示扫描量热仪(DSC)等技术对Al-Zn-Mg-Cu-Zr-0.12Ce合金铸态组织及均匀化退火过程中的组织演变进行研究。结果表明:该合金铸态组织存在严重的枝晶偏析,主要由α(Al)基体、α(Al)+Mg(Zn,Al,Cu)_2非平衡共晶组织以及少量的θ(Al_2Cu)相、Al_8Cu_4Ce相、Al_7Cu_2Fe相构成;均匀化退火过程中,大量层片状共晶组织溶入基体,同时转变生成Al_2Cu Mg相;合金的过烧温度为474.87℃;合金的最佳单级均匀化退火工艺为465℃、40 h,这与均匀化动力学方程测算结果接近;合金经(435℃,8 h)+(470℃,32 h)双级均匀化退火处理后,回溶效果更好,主要残留相为难溶的Al_2CuMg相,少量含Fe杂质相以及Al_8Cu_4Ce相。
The microstructure of the as-cast Al-Zn-Mg-Cu-Zr-0.12Ce aluminum alloy and microstructure evolution during homogenization were investigated by means of optical microscopy(OM), scanning electron microscopy(SEM), electron probe micro-analyzer(EPMA), wavelength dispersive spectroscopy(WDS), X-ray diffractometry(XRD) and differential scanning calorimetry(DSC). The results indicate that the severe dendritic segregation exists in Al-Zn-Mg-Cu-Zr-0.12 Ce alloy ingot. The as-cast microstructure mainly involves α(Al), non-equilibrium eutectics(α(Al)+Mg(Zn, Al, Cu)_2), and small amounts of θ(Al_2Cu), Al_8Cu_4Ce and Al_7Cu_2Fe phases. During homogenization, the lamellar eutectic structures in the as-cast alloy is dissolved into the matrix, meanwhile, a transformation from Mg(Zn, Al, Cu)_2 to Al_2CuMg phase also occurs. The overburnt temperature of the alloy is 474.87 ℃. The optimum parameters of single homogenization are(465 ℃, 40 h), which is consistent with the result of homogenization kinetic analysis. The eutectic phases are eliminated more sufficiently with two-step homogenization treatment at 435 ℃ for 12 h and then at 470 ℃ for 32 h. The residual second particles after homogenization are some small Al_2CuMg, Fe-rich and Al_8Cu_4Ce phases.
The microstructure of the as-cast Al-Zn-Mg-Cu-Zr-0.12Ce aluminum alloy and microstructure evolution during homogenization were investigated by means of optical microscopy(OM), scanning electron microscopy(SEM), electron probe micro-analyzer(EPMA), wavelength dispersive spectroscopy(WDS), X-ray diffractometry(XRD) and differential scanning calorimetry(DSC). The results indicate that the severe dendritic segregation exists in Al-Zn-Mg-Cu-Zr-0.12 Ce alloy ingot. The as-cast microstructure mainly involves α(Al), non-equilibrium eutectics(α(Al)+Mg(Zn, Al, Cu)_2), and small amounts of θ(Al_2Cu), Al_8Cu_4Ce and Al_7Cu_2Fe phases. During homogenization, the lamellar eutectic structures in the as-cast alloy is dissolved into the matrix, meanwhile, a transformation from Mg(Zn, Al, Cu)_2 to Al_2CuMg phase also occurs. The overburnt temperature of the alloy is 474.87 ℃. The optimum parameters of single homogenization are(465 ℃, 40 h), which is consistent with the result of homogenization kinetic analysis. The eutectic phases are eliminated more sufficiently with two-step homogenization treatment at 435 ℃ for 12 h and then at 470 ℃ for 32 h. The residual second particles after homogenization are some small Al_2CuMg, Fe-rich and Al_8Cu_4Ce phases.
引文
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[3]WANG Gao-song,ZHAO Zhi-hao,ZHANG Yi-hang,CUI Jian-zhong.Effects of solution treatment on microstructure and mechanical properties of Al-9.0Zn-2.8Mg-2.5Cu-0.12Zr-0.03Sc alloy[J].Transactions of Nonferrous Metals Society of China,2013,23(9):2537-2542.
[4]GUO S,NING Z L,ZHANG M X,CAO F Y,SUN J F.Effects of gas to melt ratio on the microstructure of an Al-10.83Zn-3.39Mg-1.22Cu alloy produced by spray atomization and deposition[J].Materials Characterization,2014,87(1):62-69.
[5]彭勇宜,樊鹏飞,潘清林.Al-Zn-Mg-Zr合金铸锭的均匀化[J].中国有色金属学报,2015,25(10):2672-2679.PENG Yong-yi,FAN Peng-fei,PAN Qing-lin.Homogenization treatment of Al-Zn-Mg-Zr alloy ingot[J].The Chinese Journal of Nonferrous Metals,2015,25(10):2672-2679.
[6]李国峰,张新明,朱航飞,李鹏辉.7B50高强铝合金的均匀化[J].中国有色金属学报,2008,18(5):764-770.LI Guo-feng,ZHANG Xin-ming,ZHU Hang-fei,LI Peng-hui.Homogenizing treatment of 7B50 high strength aluminum alloy[J].The Chinese Journal of Nonferrous Metals,2008,18(5):764-770.
[7]MONDAL C,MUKHOPADHYAY A K.On the nature of T(Al2Mg3Zn3)and S(Al2Cu Mg)phases present in as-cast and annealed 7055 aluminum alloy[J].Materials Science&Engineering A,2005,391(1/2):367-376.
[8]CHEN Kang-hua,LIU Hong-wei,ZHANG Zhuo,LI Song,TODD R I.The improvement of constituent dissolution and mechanical properties of 7055 aluminum alloy by stepped heat treatments[J].Journal of Materials Processing Technology,2003,142(1):190-196.
[9]LI Nian-kui,CUI Jian-zhong.Microstructural evolution of high strength 7B04 ingot during homogenization treatment[J].Transactions of Nonferrous Metals Society of China,2008,18(4):769-773.
[10]DENG Yin,YIN Zhi-min,CONG Fu-guan.Intermetallic phase evolution of 7050 aluminum alloy during homogenization[J].Intermetallics,2012,26(7):114-121.
[11]FAN Xi-gang,JIANG Da-ming,MENG Qing-chang,LI Zhong.The microstructural evolution of an Al-Zn-Mg-Cu alloy during homogenization[J].Materials Letters,2011,60(12):1475-1479.
[12]LAI Jian-ping,JIANG Rong-piao,LIU Hua-shan,DUN Xiao-long,LI Yan-fen,LI Xiao-qian.Influence of cerium on microstructures and mechanical properties of Al-Zn-Mg-Cu alloys[J].Journal of Central South University,2012,19(4):869-874.
[13]CHAUBEY A K,MOHAPATRA S,JAYASANKAR K,PRADHAN S K,SATPATI B,SAHAY S S,MISHRA B K,MUKHERJEE P S.Effect of cerium addition on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy[J].Transactions of the Indian Institute of Metals,2009,62(6):539-543.
[14]胡桂云,陈送义,姜慧丽,王培吉,陈康华.稀土Ce对7A52铝合金组织与性能的影响[J].中国有色金属学报,2016,26(7):1372-1382.HU Gui-yun,CHEN Song-yi,JIANG Hui-li,WANG Pei-ji,CHEN Kang-hua.Effect of RE Ce on microstructure and properties of 7A52 aluminum alloy[J].The Chinese Journal of Nonferrous Metals,2016,26(7):1372-1382.
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[16]XIE Fan-you,YAN Xin-yan,DING Ling,ZHANG Fan,CHEN Shuang-lin,CHU M G,CHNG Y A.A study of microstructure and microsegregation of aluminum 7050 alloy[J].Materials Science and Engineering A,2003,355(1/2):144-153.
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[18]李树飞,尹登峰,余鑫祥,潘康观,袁新雄,房洪杰.新型Al-Cu-Li-X合金热处理强化及组织特征[J].中国有色金属学报,2016,26(1):7-15.LI Shu-fei,YIN Deng-feng,YU Xin-Xiang,PAN Kang-guan,YUAN Xin-xiong,FANG Hong-jie.Heat treatment strengthening and microstructure characteristics of novel Al-Cu-Li-X alloy[J].The Chinese Journal of Nonferrous Metals,2016,26(1):7-15.
[19]王经涛,崔建忠.元素之间的交互作用强度及其在铸态稀土铝合金中的应用[J].西安建筑科技大学学报(自然科学版),1993,25(4):445-449.WANG Jing-tao,CUI Jian-zhong.Interaction intensity of alloying elements and its application in as-cast aluminum alloys with rare earth additions[J].Journal of Xi’an Institute of Metallurgy and Construction Engineering(Natural Science),1993,25(4):445-449.
[20]赵志浩,王静,左玉波,崔建忠.均匀化处理对低频电磁铸造7050铝合金微观组织的影响[J].金属学报,2007,43(9):956-960.ZHAO Zhi-hao,WANG Jing,ZUO Yu-bo,CUI Jian-zhong.Effect of homogenization treatment on the microstructures of low frequency electromagnetic casting 7050 aluminum alloy[J].Acta Metallurgica Sinica,2007,43(9):956-960.
[21]LI Wen-bin,PAN Qing-lin,XIAO Yan-ping,HE Yun-bin,LIU Xiao-yan.Microstructural evolution of ultra-high strength Al-Zn-Cu-Mg-Zr alloy containing Sc during homogenization[J].Transactions of Nonferrous Metals Society of China,2011,21(10):2127-2133.
[22]LIU Xiao-yan,PAN Qing-lin,FAN Xi,HE Yun-bin,LI Wen-bin,LIANG Wen-jie.Microstructural evolution of Al-Cu-Mg-Ag alloy during homogenization[J].Journal of Alloys&Compounds,2009,484(1/2):790-794.
[23]LIU Yan,JIANG Da-ming,XIE Wen-long,HU Jie,MA Bo-ran.Solidification phases and their evolution during homogenization of a DC cast Al-8.35-Zn-2.5Mg-2.25Cu alloy[J].Materials Characterization,2014,93:173-183.