Gravity-Induced Convection during Directional Solidification of Hypermonotectic Alloys

Abstract:

A two-phase volume-averaging model developed for the simulation of the dynamic decomposition and solidification of hypermonotectic alloys was used to study the occurrence of convection phenomena during directional solidification of a hypermonotectic alloy (Al-10 wt.%Bi) under terrestrial condition. The model accounts for nucleation and growth of secondary phase droplets, Marangoni and Stokes forces, solute partitioning, heat release due to decomposition and solidification. It is shown that the appearance and growth of secondary droplets is accompanied with a continuous downwards motion of droplets, which rapidly becomes unstable. After relaxation of this dynamic motion the advancing solidification front freezes in the resulting non-uniform droplet distribution.

• Periodical: Materials Science Forum (Volume 508)
• Pages: 193-198
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.508.193
• Online since: March 2006
• Authors: Andreas Ludwig, Meng Huai Wu, M. Abondano, Lorenz Ratke
• Keywords: Convection, Decomposition, Directional Solidification, Droplet Motion, Hypermonotectic, Modeling, Phase Distribution

References

[1] B. Prinz, A. Romero and L. Ratke: J. Mater. Sci. Vol. 30(1995), p.4715.

[2] J. Alkemper and L. Ratke: Z. Metallkd. Vol. 85 (1994), p.365.

[3] L. Ratke, G. Korekt and S. Drees: Adv. Space Res. Vol. 22 (1998, p.1227.

[4] L. Ratke and G. Korekt: Z. Metallkd. Vol. 91 (2000), p.919.

[5] H.U. Walter: Proc. RIT/ESA/SSC Workshop: ESA SP 219 ed Järva Krog (Noordwijk, Sweden 1984), p.47.

[6] C. Beckermann and R. Viskanta: Appl. Mech. Rev. Vol. 46 (1993), p.1.

[7] J. Ni and C. Beckermann: Metall. Trans. Vol. 22B (1991), p.349.

[8] C.Y. Wang and C. Beckermann: Metall. Mater. Trans. Vol. 27A (1996), p.2754.

[9] C.Y. Wang and C. Beckermann: Metall. Mater. Trans. Vol. 27A (1996), p.2765.

[10] C.Y. Wang and C. Beckermann: Metall. Mater. Trans. Vol. 27A (1996), p.2784.

[11] C. Beckermann: JOM Vol. 49 (1997), p.13.

[12] A.V. Reddy and C. Beckermann: Metall. Mater. Trans. Vol. 28B (1997), p.479.

[13] A. Ludwig and M. Wu: Metall. Mater. Trans. Vol. 33A (2002), p.3673.

[14] M. Wu, A. Ludwig, P.R. Sahm and A. Bührig-Polaczek: Proc. MCWASP X ed D M Stefanescu et al (Warrendale, PA: Minerals, Metals and Materials Society 2003), p.261.

[15] M. Wu, A. Ludwig, A. Bührig-Polaczek, M. Fehlbier and P.R. Sahm: Inter. J. Heat Mass Transfer Vol. 46 (2002), p.2819.

DOI: 10.1016/s0017-9310(03)00054-1

[16] M. Wu, A. Ludwig and L. Ratke: Modell. Simu. Mater. Sci. Eng. Vol. 11 (2003), P. 755.

[17] M. Wu, A. Ludwig and L. Ratke: Metall. Mater. Trans. Vol. 34A (2003), p.3009.

[18] M. Wu and A. Ludwig: Adv. Eng. Mater. Vol. 5, No. 1 (2003), p.62.

[19] H. Fujii, T. Kimura, H. Kitaguchi, H. Kumakura and K. Togano: J. Mater. Sci. Vol. 30 (1995), p.3429.