Abstract
The microstructure of the as-cast 7A55 aluminum alloy and its evolution during homogenization were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The results indicate that the microstructure of the as-cast 7A55 aluminum alloy mainly consists of the dendritic network of aluminum solid solution, Al/AlZnMgCu eutectic phases, and intermetallic compounds MgZn2, Al2CuMg, Al7Cu2Fe, and Al23CuFe4. After homogenization at 470°C for 48 h, Al/AlZnMgCu eutectic phases are dissolved into the matrix, and a small amount of high melting-point secondary phases were formed, which results in an increasing of the starting melting temperature of 7A55 aluminum alloy. The high melting-point secondary phases were eliminated mostly when the homogenization time achieved to 72 h. Therefore, the reasonable homogenization heat treatment process for 7A55 aluminum alloy ingots was chosen as 470°C/72 h.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Chen K.H., Liu H.W., and Liu Y.Z., The effect of promotively-solutionizing treatment on the mechanical properties and fracture of ultra high strength 7055 aluminum alloys, J. Central South Univ. Technol., 2000, 31(6): 528.
Starke E.A. Jr, and Staley J.T., Application of modern aluminum alloys to aircraft, Prog. Aerospace Sci., 1996, 32: 131
Chen W., Application of advanced aluminum alloys in A380 structures. Aviation Maintenance & Engineering, 2005(2): 40.
Feng C., Liu Z.Y., Ning A.L., Liu Y.B., and Zeng S.M., Retrogression and re-aging treatment of Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr aluminum alloy, Trans. Nonferrous Met. Soc. China, 2006, 16: 1163.
Chen K.H., Liu H.W., Zhang Z., Li S., and Richard I.T., The improvement of constituent dissolution and mechanical properties of 7055 aluminum alloy by stepped heat treatments, J. Mater. Process. Technol., 2003, 142: 190.
Zhang X.M., Huang Z.B., and Liu S.D., Effects of two-stage solution on microstructures and mechanical properties of 7A55 aluminum alloy, Chin. J. Nonferrous Met., 2006, 16(9): 1527.
Chen J.Z., Zhen L., Yang S.J., Shao W.Z., and Dai S.L., Investigation of precipitation behavior and related hardening in AA 7055 aluminum alloy, Mater. Sci. Eng. A, 2009, 500: 34.
Peng B.S., Ning K.Q., and Zeng S.M., Effects of two-peak aging treatment on microstructure and mechanical properties of 7055 Aluminum Alloy, J. Shaoyang Univ. (Nat. Sci.e Ed.), 2009, 6(2): 32.
Feng C., Liu Z.Y., Ning A.L., and Zeng S.M., Effect of low temperature aging on microstructure and mechanical properties of super-high strength aluminum alloy, J. Central South Univ. Technol., 2006, 13(5): 461.
Liu S.D., Zhang X.M., Chen M.A., and You J.H., Influence of aging on quench sensitivity effect of 7055 aluminum alloy, Mater. Charact., 2008, 59: 53.
Liu S.D., Zhang X.M., Huang Z.B., and You J.H., Prediction of hardness of aluminum alloy 7055 by quench factor analysis, Mater. Sci. Forum, 2007, 546–549: 881.
Liu S.D., Zhong Q.M., Zhang Y., Liu W.J., Zhang X.M., and Deng Y.L., Investigation of quench sensitivity of high strength Al-Zn-Mg-Cu alloys by time-temperature-properties diagrams, Mater. Des., 2010, 31: 3116.
Li Y.X., Li P., Zhao G., Liu X.T., and Cui J.Z., The constituents in Al-10Zn-2.5Mg-2.5Cu aluminum alloy, Mater. Sci. Eng. A, 2005, 397: 204.
Mondal C. and Mukhopadhy A.K., On the nature of T (Al2Mg3Zn3) and S (Al2CuMg) phases present in as-cast and annealed 7055 aluminum alloy, Mater. Sci. Eng. A, 2005, 391: 367.
Lu Y.L., Li M.Q., Li X.C., and Li X.P., Microscopic characterization of semi-solid aluminium alloys, Int. J. Miner. Metall. Mater., 2010, 17: 290.
Hou L.G., Cai Y.H., Cui H., and Zhang J.S., Microstructure evolution and phase transformation of traditional cast and spray-formed hypereutectic aluminium-silicon alloys induced by heat treatment, Int. J. Miner. Metall. Mater., 2010, 17: 297.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lv, X., Guo, E., Li, Z. et al. Research on microstructure in as-cast 7A55 aluminum alloy and its evolution during homogenization. Rare Metals 30, 664–668 (2011). https://doi.org/10.1007/s12598-011-0446-7
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12598-011-0446-7