Microstructure and mechanical properties of 7A56 aluminum alloy after solution treatment


The effect of solution treatment on the microstructure and mechanical properties of a novel 7A56 aluminum alloy plate was investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), conductivity, hardness and tensile tests. The results indicate that the coarse second phases in the hot-rolled plate mainly consist of AlZnMgCu quaternary phase and Al7Cu2Fe phase, and no Al2CuMg phase is found. The amount of the second phases gradually reduces with the increase in temperature (450–480 °C) and time (1–8 h) during the solution treatment, and the soluble particles are completely dissolved into the matrix after solution treatment at 470 °C for 4 h, while the residual phases are mainly Fe-rich phase along the grain boundaries. The recrystallization fraction of the alloy gradually increases with the degree of solution treatment deepened. When the temperature exceeds 480 °C, over-burning takes place. The mechanical properties of samples treated at 470 °C for various times were tested. After the solution treated at 470 °C for 4 h, the quenching conductivity and peak-aged hardness of the alloy are 30.8%IACS and HV 204, respectively. The ultimate tensile strength and yield strength of the samples aged at 120 °C for 24 h are 661 and 588 MPa, respectively.

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  1. [1]

    Rometsch PA, Zhang Y, Knight S. Heat treatment of 7xxx series aluminium alloys-some recent developments. Trans Nonferrous Met Soc China. 2014;24(7):2003.

    CAS  Article  Google Scholar 

  2. [2]

    Xu DK, Birbilis N, Lashansky D, Rometsch PA, Muddle BC. Effect of solution treatment on the corrosion behaviour of aluminium alloy AA7150: optimisation for corrosion resistance. Corros Sci. 2011;53(1):217.

    CAS  Article  Google Scholar 

  3. [3]

    Chen ZY, Mo Y, Nie ZR. Effect of Zn content on the microstructure and properties of super-high strength Al–Zn–Mg–Cu alloys. Metall Mater Trans A. 2013;44(8):3910.

    CAS  Article  Google Scholar 

  4. [4]

    Peng GS, Chen KH, Chen SY, Fang HC. Evolution of the second phase particles during the heating-up process of solution treatment of Al–Zn–Mg–Cu alloy. Mater Sci Eng A. 2015;641(12):237.

    CAS  Article  Google Scholar 

  5. [5]

    Li PY, Xiong BQ, Zhang YA, Li ZH. Temperature variation and solution treatment of high strength AA7050. Trans Nonferrous Met Soc China. 2012;22(3):546.

    Article  Google Scholar 

  6. [6]

    Williams JC, Starke EA. Progress in structural materials for aerospace systems. Acta Mater. 2003;51(19):5775.

    CAS  Article  Google Scholar 

  7. [7]

    Liu JT, Zhang YA, Li XW, Li ZH, Xiong BQ, Zhang JS. Thermodynamic calculation of high zinc-containing Al–Zn–Mg–Cu alloy. Trans Nonferrous Met Soc China. 2014;24(5):1481.

    CAS  Article  Google Scholar 

  8. [8]

    Dumont D, Deschamps A, Bréchet Y. Characterization of precipitation microstructures in aluminum alloys 7040 and 7050 and their relationship to mechanical behavior. Mater Sci Technol. 2004;20(5):567.

    CAS  Article  Google Scholar 

  9. [9]

    Wen K, Fan YQ, Wang GJ, Jin LB, Li XW, Li ZH, Zhang YA, Xiong BQ. Aging behavior and precipitate characterization of a high Zn-containing Al–Zn–Mg–Cu alloy with various tempers. Mater Des. 2016;101(7):16.

    CAS  Article  Google Scholar 

  10. [10]

    Lang YJ, Zhou GX, Hou LG, Zhang JS, Zhuang LZ. Significantly enhanced the ductility of the fine-grained Al–Zn–Mg–Cu alloy by strain-induced precipitation. Mater Des. 2015;88(9):625.

    CAS  Article  Google Scholar 

  11. [11]

    Robson JD. Microstructural evolution in aluminum alloy 7050 during processing. Mater Sci Eng A. 2004;382(1–2):112.

    Article  Google Scholar 

  12. [12]

    Fang HC, Chen KH, Chen X, Chao H, Peng GS. Effect of Cr, Yb and Zr additions on localized corrosion of Al–Zn–Mg–Cu alloy. Corros Sci. 2009;51(12):2872.

    CAS  Article  Google Scholar 

  13. [13]

    Fan XG, Jiang DM, Meng QC. The microstructural evolution of an Al–Zn–Mg–Cu alloy during homogenization. Mater Lett. 2006;60(12):1475.

    CAS  Article  Google Scholar 

  14. [14]

    Xie F, Yan X, Ding L, Zhang F, Chen S. A study of microstructure and microsegregation of aluminum 7050 alloy. Mater Sci Eng A. 2003;355(1–2):144.

    Article  Google Scholar 

  15. [15]

    Li DF, Zhang DZ, Liu SD, Shan ZJ, Zhang XM, Wang Q, Han SQ. Dynamic recrystallization behavior of 7085 aluminum alloy during hot deformation. Trans Nonferrous Met Soc China. 2016;26(6):1491.

    CAS  Article  Google Scholar 

  16. [16]

    Xu DK, Rometsch PA, Birbilis N. Improved solution treatment for an as-rolled Al-Zn-Mg-Cu alloy. Part II. Microstructure and mechanical properties. Mater. Sci. Eng A. 2012;534(2):244.

    CAS  Article  Google Scholar 

  17. [17]

    Xu DK, Rometsch PA, Birbilis N. Improved solution treatment for an as-rolled Al–Zn–Mg–Cu alloy. Part I. Characterisation of constituent particles and overheating. Mater. Sci. Eng A. 2012;534(2):234.

    CAS  Article  Google Scholar 

  18. [18]

    Bolouri A, Shahmiri M, Cheshmeh ENH. Microstructural evolution during semisolid state strain induced melt activation process of aluminum 7075 alloy. Trans Nonferrous Met Soc China. 2010;20(9):1663.

    CAS  Article  Google Scholar 

  19. [19]

    Ralph B. Light Alloys: From Traditional Alloys to Nanocrystals. 4th ed. Oxford: Butterworth-Heinemann; 2006. 421.

    Google Scholar 

  20. [20]

    Mazzer EM, Afonso CRM, Galano M. Microstructure evolution and mechanical properties of Al–Zn–Mg–Cu alloy reprocessed by spray-forming and heat treated at peak aged condition. J Alloys Compd. 2013;579(12):169.

    CAS  Article  Google Scholar 

  21. [21]

    Morere B, Ehrström JC, Gregson PJ. Microstructural effects on fracture toughness in AA7010 plate. Metall Mater Trans A. 2000;31(10):2503.

    Article  Google Scholar 

  22. [22]

    Zhang Y, Bettles C, Rometsch PA. Effect of recrystallisation on Al3Zr dispersoid behaviour in thick plates of aluminium alloy AA7150. J Mater Sci. 2014;49(4):1709.

    CAS  Article  Google Scholar 

  23. [23]

    Starink MJ, Milkereit B, Zhang Y. Predicting the quench sensitivity of Al–Zn–Mg–Cu alloys: a model for linear cooling and strengthening. Mater Des. 2015;88(12):958.

    CAS  Article  Google Scholar 

  24. [24]

    Marlaud T, Malki B, Henon C, Deschamps A, Baroux B. Relationship between alloy composition, microstructure and exfoliation corrosion in Al–Zn–Mg–Cu alloys. Corros Sci. 2011;53(10):3139.

    CAS  Article  Google Scholar 

  25. [25]

    Feng C, Liu ZY, Ning AL, Liu YB, Zeng SM. 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(5):1163.

    CAS  Article  Google Scholar 

  26. [26]

    Ryum N. The influence of a precipitate-free zone on the mechanical properties of an Al–Mg–Zn alloy. Acta Metall. 1968;16(3):327.

    CAS  Article  Google Scholar 

  27. [27]

    Zhang YH, Yang SC, Zhi JH. Microstructure evolution in cooling process of Al–Zn–Mg–Cu alloy and kinetics description. Trans Nonferrous Met Soc China. 2012;22(9):2087.

    CAS  Article  Google Scholar 

  28. [28]

    Yang W, Ji S, Zhang Q, Wang M. Investigation of mechanical and corrosion properties of an Al–Zn–Mg–Cu alloy under various ageing conditions and interface analysis of η′ precipitate. Mater Des. 2015;85(15):752.

    CAS  Article  Google Scholar 

  29. [29]

    Gang S, Alfred C. Early-stage precipitation in Al–Zn–Mg–Cu alloy (7050). Acta Mater. 2004;52(15):4503.

    Article  Google Scholar 

  30. [30]

    Cai B, Adams BL, Nelson TW. Relation between precipitate-free zone width and grain boundary type in 7075-T7 Al alloy. Acta Mater. 2007;55(5):1543.

    CAS  Article  Google Scholar 

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This work was financially supported by the National Key Research and Development Program of China (No. 2016YFB0300803), the National Natural Science Foundation of China (No. 51274046) and the National Key Basic Research Program (No. 2012CB619504).

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Correspondence to Bao-Hong Zhu.

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Guo, FB., Zhu, BH., Jin, LB. et al. Microstructure and mechanical properties of 7A56 aluminum alloy after solution treatment. Rare Met. 40, 168–175 (2021). https://doi.org/10.1007/s12598-017-0985-7

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  • 7A56 aluminum alloy
  • Solution treatment
  • Aging treatment
  • Microstructure
  • Properties