ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 21    No. 10    October 2011

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Microstructural evolution of ultra-high strength Al-Zn-Cu-Mg-Zr alloy containing Sc during homogenization
LI Wen-bin1, 2, PAN Qing-lin1, XIAO Yan-ping1, HE Yun-bin1, LIU Xiao-yan1
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. School of Civil Engineering, Hunan City University, Yiyang 413000, China
)
Abstract: The microstructural evolution and composition distribution of an Al-Zn-Cu-Mg-Sc-Zr alloy during homogenization were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that severe dendritic segregation exists in Al-Zn-Cu-Mg-Sc-Zr alloy ingot. There are a lot of eutectic phases at grain boundary and the distribution of the main elements varies periodically along interdendritic region. The main eutectic phases at grain boundary are Al7Cu2Fe phase and T (Al2Mg3Zn3). The residual phases are dissolved into the matrix gradually during homogenization with increasing temperature and prolonging holding time, which can be described by a constitutive equation in exponential function. The overburnt temperature of the alloy is 473.9 °C. The optimum parameters of homogenization are 470 °C and 24 h, which is consistent with the result of homogenization kinetic analysis.
Key words: Al-Zn-Cu-Mg-Sc-Zr alloy; homogenization; microstructural evolution; overburnt temperature; homogenization kinetics
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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