Effect of Grain Refinement on the Dendrite Coherency Point during Solidification of the A319 Aluminum Alloy



Dendrite coherency is important to the formation of the solidification structure and castability of alloys. The effects of grain refinement on the dendrite coherency in A319 aluminum alloy have been studied using the two-thermocouple thermal analysis technique in the solidifying sample. The fraction solid at the dendrite coherency point (\( f_{s}^{\text{DCP}} \)) in the A319 alloy increases with increasing Al-5Ti-1B grain refiner, and varies from 16 to 21 pct when the amount of Al-5Ti-1B in the alloy is in the range of 0 to 4.6 wt pct. The results also indicate that the grain refinement increases the temperature interval of coherency (T N – T DCP) and coherency time (t DCP), and it can postpone dendrite coherency. These changes were interpreted based on the dendrite growth rate, the growth restriction factor, and the microstructure.


Coherency Time Nucleation Temperature Mold Filling Shrinkage Porosity Dendritic Network 


  1. 1.
    L. Backuerud, G. Chai, and J. Tamminen: Solidification Characteristics of Aluminum Alloys, vol. 2, Foundry Alloys, AFS/Skanaluminium, Stockholm, 1990.Google Scholar
  2. 2.
    L. Arnberg, L. Backerud, and G. Chai: Solidification Characteristics of Aluminum Alloys, vol. 3, Dendrite Coherency, AFS, Des Plaines, IL, 1996.Google Scholar
  3. 3.
    H. Jiang, W.T. Kierkus, and J.H. Sokolowski: AFS Trans., 1999, vol. 107, pp. 169–72.Google Scholar
  4. 4.
    G. Chai, L. Backerud, T. Rolland, and L. Arnberg: Metall. Mater. Trans. A, 1995, vol. 26A, pp. 965–70.CrossRefGoogle Scholar
  5. 5.
    N.L.M. Veldman, A.K. Dahle, D.H. Stjohn, and L. Arnberg: Metall. Mater. Trans. A, 2001, vol. 32A, pp. 147–55.CrossRefGoogle Scholar
  6. 6.
    L. Backerud and B. Chalmers: Trans. TMS-AIME, 1969, vol. 245, pp. 309–18.Google Scholar
  7. 7.
    J. Tamminen: Ph.D. Thesis, published in Chemical Communications, University of Stockholm, Stockholm, 1988, No. 2.Google Scholar
  8. 8.
    M.B. Djurdjevic, W.T. Kierkus, G.E. Byczynski, T.J. Stockwell, and J.H. Sokolowski: AFS Trans., 1999, vol. 107, pp. 173–79.Google Scholar
  9. 9.
    J. Campbell: Casting, 2nd ed., Butterworth-Heinemann Ltd., Oxford, United Kingdom, 2003.Google Scholar
  10. 10.
    L. Arnberg, A.K. Dahle, C.J. Paradies, and F. Syvertsen: AFS Trans., 1995, vol. 103, pp. 753–59.Google Scholar
  11. 11.
    L. Arnberg, G. Chai, and L. Backerud: Mater. Sci. Eng., 1993, vol. A173, pp. 101–03.Google Scholar
  12. 12.
    R.I. Mackay, M.B. Djurdjevic, and J.H. Sokolowski: AFS Trans., 2000, vol. 108, pp. 521–30.Google Scholar
  13. 13.
    M. Johnsson: Z. Metallkd., 1994, vol. 85, pp. 781–85.Google Scholar
  14. 14.
    D. Emadi and L.V. Whiting: AFS Trans., 2002, vol. 200, No. 033.Google Scholar
  15. 15.
    J.O. Barlow and D.M. Stefanescu: AFS Trans., 1997, vol. 105, pp. 349–54.Google Scholar
  16. 16.
    S.G. Shabestari and M. Malekan: Can. Metall. Q., 2005, vol. 44 (3), pp. 305–12.Google Scholar
  17. 17.
    S.G. Shabestari and S. Ghodrat: Mater. Sci. Eng. A, 2007, vol. 467, pp. 150–58.CrossRefGoogle Scholar
  18. 18.
    M.B. Djurdjevic, W.T. Kierkus, R.E. Liliac, and J.H. Sokolowski: 41st Ann. Conf. of Metallurgists of CIM 2002, Proc. Int. Symp. on Light Metals, The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), Montreal, Canada, pp. 351–65.Google Scholar
  19. 19.
    R.C. Zamarripa, J.A.R. Salas, J.T. Silva, S. Valtierra, and R. Colas: Metall. Mater. Trans. A, 2007, vol. 38A, pp. 1875–79.CrossRefADSGoogle Scholar
  20. 20.
    O. Cabrera, M. Ramírez, B. Campillo, and C. González-Rivera: Mater. Manufact. Process., 2008, vol. 23, pp. 46–50.CrossRefGoogle Scholar
  21. 21.
    A.K. Dahle and D.H. StJohn: Acta Mater., 1999, vol. 47 (1), pp. 31–41.CrossRefGoogle Scholar
  22. 22.
    T. Sumitomo, D.H. StJohn, and T. Steinberg: Mater. Sci. Eng. A, 2000, vol. 289, pp. 18–29.CrossRefGoogle Scholar
  23. 23.
    K.G. UPadhya, D.M. Stefanescu, K. Lieu, and D.P. Yeager: AFS Trans., 1989, vol. 97 pp. 61–66.Google Scholar
  24. 24.
    J. Campbell: AFS Cast Met. Res. J., 1969, vol. 5, pp. 1–8.Google Scholar

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© The Minerals, Metals & Materials Society and ASM International 2009

Authors and Affiliations

  1. 1.Faculty of Materials and Metallurgical EngineeringIran University of Science and Technology (IUST)NarmakIran

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