Quantitative Investigation of Precipitates in a High-Zinc Al–9.54Zn–2.10Mg–1.69Cu Alloy with Various Typical Tempers

  • Kai Wen
  • Bai-Qing Xiong
  • Yong-An Zhang
  • Xi-Wu Li
  • Zhi-Hui Li
  • Shu-Hui Huang
  • Li-Zhen Yan
  • Hong-Wei Yan
  • Hong-Wei Liu
Conference paper

Abstract

In order to analyze single stage ageing behavior of a high-zinc Al–9.54Zn–2.10Mg–1.69Cu alloy, the microstructure of the alloy subjected to T6, T76 and T77 states are investigated via transmission electron microscopy (TEM) combined with high-resolution transmission electron microscopy (HRTEM) attached to it. Under the premise in precipitate observations, diameter distributions and average diameter size of precipitates are deduced from Bright-Field TEM (BF TEM) images projected along \( \left\langle {110} \right\rangle_{\text{Al}} \) orientation with the help of an image processing. The results indicate that the main precipitates are GPII zone and η′ phase in the T6 and T77 alloys while η′ and η phase in the T74 alloy. The Bright field TEM observations reveal that the matrix precipitates for the T6 and T77 alloys have small size and dispersive distribution while that for the T74 alloy has big size and sparse distribution. Quantitative precipitate characteristics including diameter distribution and average diameter size have been gained by an image processing relying on BF TEM images projected along \( \left\langle {110} \right\rangle_{\text{Al}} \) orientation. The results reveal that the T6 and T77 alloys have more than a half percentage of precipitates with a size less than 2 nm while the T77 and T74 alloys have broad precipitate distribution range till 14 and 16 nm, respectively. The grain boundary precipitates (GBPs) for the T6 alloy have continuous distribution with small size while that for the T74 and T77 alloys distribute intermittently with big size.

Keywords

Al–Zn–Mg–Cu alloy High-zinc Ageing treatment Precipitate 

Notes

Acknowledgements

This study was financially supported by the National Key R&D Program of China (No. 2016YFB0300803, 2016YFB0300903).

References

  1. 1.
    A.S. Prosviryakov, K.D. Shcherbachev, Strengthening of mechanically alloyed Al-based alloy with high Zr contents, Mater. Sci. Eng. A 713 (2018) 174–179.Google Scholar
  2. 2.
    Y. Zhang, D. Pelliccia, B. Milkereit, N. Kirby, M.J. Starink, P.A. Rometsch, Analysis of age hardening precipitates of Al-Zn-Mg-Cu alloys in a wide range of quenching rates using small angle X-ray scattering, Mater. Des. 142 (2018) 259–267.Google Scholar
  3. 3.
    T. Dursun, C. Soutis, Recent developments in advanced aircraft aluminium alloys, Mater. Des. 56 (2014) 862–871.Google Scholar
  4. 4.
    S.B. Pankade, D.S. Khedekar, C.L. Gogte, The influence of heat treatments on electrical conductivity and corrosion performance of AA 7075-T6 aluminium alloy, Procedia Manufac. 20 (2018) 53–58.Google Scholar
  5. 5.
    P.A. Rometsch, Y. Zhang, S. Knight, Heat treatment of 7xxx series aluminium alloys—some recent developments, Trans. Nonferrous Metals Soc. 24 (2014) 2003–2017.Google Scholar
  6. 6.
    H. Li, F. Cao, S. Guo, Z. Ning, Z. Liu, Y. Jia, S. Scudino, T. Gemming, J. Sun, Microstructures and properties evolution of spray-deposited Al-Zn-Mg-Cu-Zr alloys with scandium addition, J. Alloy Compd 691 (2017) 482–488.Google Scholar
  7. 7.
    M. Chemingui, M. Khitouni, K. Jozwiak, G. Mesmacque, A. Kolsi, Characterization of the mechanical properties changes in an Al-Zn-Mg alloy after a two-step ageing treatment at 70° and 135°C, Mater. Des. 31 (2010) 3134–3139.Google Scholar
  8. 8.
    P. Xia, Z. Liu, S. Bai, L. Lu, L. Gao, Enhanced fatigue crack propagation resistance in a superhigh strength Al–Zn–Mg–Cu alloy by modifying RRA treatment, Mater. Character. 118 (2016) 438–445.Google Scholar
  9. 9.
    Y.P. Xiao, Q.L. Pan, W.B. Li, X.Y. Liu, Y.B. He, Influence of retrogression and re-ageing treatment on corrosion behaviour of an Al-Zn-Mg-Cu alloy, Mater. Des. 32 (2011) 2149–2156.Google Scholar
  10. 10.
    L. Ding, Z. Jia, J.F. Nie, Y. Weng, L. Cao, H. Chen, X. Wu, Q. Liu, The structural and compositional evolution of precipitates in Al-Mg-Si-Cu alloy, Acta Mater. 145 (2018) 437–450.Google Scholar
  11. 11.
    G. Sha, A. Cerezo, Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050), Acta Mater. 52 (2004) 4503–4516.Google Scholar
  12. 12.
    X. Peng, Y. Li, X. Liang, Q. Guo, G. Xu, Y. Peng, Z. Yin, Precipitate behavior and mechanical properties of enhanced solution treated Al-Zn-Mg-Cu alloy during non-isothermal ageing, J. Alloy Compd. 735 (2018) 964–974.Google Scholar
  13. 13.
    A. Zindal, J. Jain, R. Prasad, S.S. Singh, R. Sarvesha, P. Cizek, M.R. Barnett, Effect of heat treatment variables on the formation of precipitate free zones (PFZs) in Mg-8Al-0.5 Zn alloy, Mater. Character. 136 (2018) 175–182.Google Scholar
  14. 14.
    Y.C. Lin, J. Zhang, G. Liu, Y. Liang, Effects of pre-treatments on ageing precipitates and corrosion resistance of a creep-aged Al-Zn-Mg-Cu alloy, Mater. Des. 83 (2015) 866–875.Google Scholar
  15. 15.
    M.V. Markushev, E.V. Avtokratova, S.V. Krymskiy, O.S. Sitdikov, Effect of precipitates on nanostructuring and strengthening of high-strength aluminum alloys under high pressure torsion, J. Alloy Compd. 743 (2018) 773–779.Google Scholar
  16. 16.
    Y. Liu, D. Jiang, B. Li, Y. Hu, Heating ageing behavior of Al-8.35Zn-2.5 Mg-2.25Cu alloy, Mater. Des. 60 (2014) 116–124.Google Scholar
  17. 17.
    D.M. Liu, B.Q. Xiong, F.G. Bian, Z.H. Li, X.W. Li, Y.A. Zhang, et al., Quantitative study of precipitates in an Al-Zn-Mg-Cu alloy aged with various typical tempers, Mater. Sci. Eng. A 588 (2013) 1–6.Google Scholar
  18. 18.
    Y.C. Lin, X.B. Peng, Y.Q. Jiang, C.J. Shuai, Effects of creep-aging parameters on aging precipitates of a two-stage creep-aged Al–Zn–Mg–Cu alloy under the extra compressive stress, J. Alloy Compd. 743 (2018) 448–455.Google Scholar
  19. 19.
    K. Wen, B. Xiong, Y. Zhang, Z. Li, X. Li, S. Huang, L. Yan, H. Yan, H. Liu, Over-aging influenced matrix precipitate characteristics improve fatigue crack propagation in a high Zn-containing Al-Zn-Mg-Cu alloy, Mater. Sci. Eng. A 716 (2018) 42–54.Google Scholar
  20. 20.
    J.W. Martin. Precipitation Hardening, Butterworth-Heinemann, Oxford, 1998.Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Kai Wen
    • 1
  • Bai-Qing Xiong
    • 1
  • Yong-An Zhang
    • 1
  • Xi-Wu Li
    • 1
  • Zhi-Hui Li
    • 1
  • Shu-Hui Huang
    • 1
  • Li-Zhen Yan
    • 1
  • Hong-Wei Yan
    • 1
  • Hong-Wei Liu
    • 1
  1. 1.State Key Laboratory of Non-ferrous Metals and ProcessesGeneral Research Institute for Nonferrous MetalsBeijingChina

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