Abstract
Creep-resistant Mg-4Al-4Ca (AX44) alloy was solidified under different growth/cooling rates using a directional solidification (DS) technique. The solidification behavior and microsegregation of the alloying elements in the castings was investigated. Computational thermodynamics calculations of phase equilibria and experimental observations confirm that the solidification microstructure in this alloy consists of α-Mg, C36-(Mg,Al)2Ca, and C14-Mg2Ca phases. A relationship was established between the primary dendrite arm spacing and the cooling rate, which can be used to predict mechanical properties such as yield strength and creep. The microsegregation of alloying elements (Al and Ca) predicted by the Scheil model in AX44 agrees well with the electron probe microanalysis (EPMA) measurements, suggesting that the Scheil model can be used in microstructure simulation of magnesium castings.
Similar content being viewed by others
References
K.U. Kainer: Magnesium—Alloys and Technologies, Wiley-VCH, Weinheim, Germany, 2003, p. 254.
A.A. Luo: Int. Mater. Rev., 2004, vol. 49, pp. 13–16.
E. Baril and P. Labelle: JOM, 2003, vol. 55, pp. 34–38.
M.O. Pekguleryuz and A.A. Luo: Patent WO96/25529, 1996.
B.R. Powell, V. Rezhets, A.A. Luo, and B.L. Tiwari: U.S. Patent 6,264,763, 2001.
A.A. Luo, M.P. Balogh, and B.R. Powell: Metall. Mater. Trans. A, 2007, vol. 33A, pp. 567–70.
J. Grobner, D. Kevorkov, I. Chumak, and Schmid-Fetzer: R.Z. Metall., 2003, vol. 94, pp. 976–81.
K. Ozturk, Y. Zhong, A.A. Luo, and Z.-K. Liu: JOM, 2003, vol. 55, pp. 40–46.
Y. Zhong, A.A. Luo, J.O. Sofo, and Z-K Liu: Mater. Sci. Forum., 2005, vols. 488–489, pp. 169–73.
H. Cao, C. Zhang, J. Zhu, G. Cao, S. Kou, R. Schmid-Fetzer, and Y.A. Chang: Acta Mater., 2008, vol. 56, pp. 5245–52.
A. Janz, J. Grobner, H. Cao, J. Zhu, Y.A. Chang, and R. Schmid-Fetzer: Acta Mater., 2009, vol. 57, pp. 682–88.
A. Suzuki, N.D. Saddock, J.W. Jones, and T.M. Pollock: Acta Mater., 2005, vol. 53, pp. 2823–29.
A. Suzuki, N.D. Saddock, J.W. Jones, and T.M. Pollock: Scripta Mater., 2004, vol. 51, pp. 1005–11.
A. Suzuki, N.D. Saddock, J.W. Jones, and T.M. Pollock: Metall. Mater. Trans. A, 2006, vol. 37A, pp. 975–82.
L.H. Han, H. Hu, and D.O. Northwood: Mater. Lett., 2008, vol. 62, pp. 381–84.
S.M. Zhu, B.L. Mordike, and J.F. Nie: Mater. Sci. Eng. A, 2008, vols. 483–484, pp. 583–89.
X. Yan, S. Chen, F. Xie, and Y.A. Chang: Acta Mater., 2002, vol. 50, pp. 2199–2205.
X. Yan, F. Xie, M. Chu, and Y.A. Chang: Mater. Sci. Eng. A, 2001, vol. 302, pp. 268–74.
C. Zhang, D. Ma, K.S. Wu, H.B. Cao, G.P. Cao, S. Kou, and Y.A. Chang: Intermetallics, 2007, vol. 15, pp. 1395–1401.
CompuTherm LLC: Pandat 8.0—Phase Diagram Calculation Software for Multi-Component Systems, CompuTherm LLC, Madison, WI, 2008.
R. Schmid-Fetzer, A. Janz, J. Grobner, and M. Ohno: Adv. Eng. Mater., 2005, vol. 7, pp. 1142–47.
M.C. Flemings: Solidification Processing, McGraw-Hill Book Co., New York, NY, 1974, p. 364.
J.D. Hunt and S.Z. Lu: Metall. Mater. Trans. A, 1996, vol. 27A, pp. 611–19.
J.R. Terbush, N.D. Saddock, J.W. Jones, and T.M. Pollock: Metall. Mater. Trans. A, vol. 41A, pp. 2435–42.
Acknowledgments
Financial support by the National Ministry of Science and Technology (Grant Nos. 2007CB613703 and 2009AA03Z521) and the Shanghai Rising-Star Program (A type, 09QA1403100) are gratefully acknowledged. Professor Austin Chang, University of Wisconsin–Madison (UW-Madison), is acknowledged for providing access to the directional solidification apparatus at UW-Madison and for many helpful discussions. It is a pity he passed away before we completed this work. Dr. Anil Sachdev, GM R&D, provided constructive suggestions and Mr. Chao Shen, UW-Madison, assisted in the DS experiments.
Author information
Authors and Affiliations
Corresponding author
Additional information
Manuscript submitted October 11, 2011.
Rights and permissions
About this article
Cite this article
Zheng, X., Luo, A.A., Zhang, C. et al. Directional Solidification and Microsegregation in a Magnesium-Aluminum-Calcium Alloy. Metall Mater Trans A 43, 3239–3248 (2012). https://doi.org/10.1007/s11661-012-1159-8
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11661-012-1159-8