Abstract
Al-Si alloys are materials that have been developed over the years to meet the increasing demands of the automotive industry for smaller, lighter-weight, high-performance components. An important alloy in this respect is the 319 alloy, wherein silicon and copper are the main alloying elements, and magnesium is often added in automotive versions of the alloy for strengthening purposes. The mechanical properties are also ameliorated by modifying the eutectic silicon structure (strontium being commonly employed) and by reducing the harmful effect of the β-Al5FeSi iron intermetallic present in the cast structure. Magnesium is also found to refine the silicon structure. The present study was undertaken to investigate the individual and combined roles of Mg and Sr on the morphologies of Si, Mg2Si, and the iron and copper intermetallics likely to form during the solidification of 319-type alloys at very slow (close to equilibrium) cooling rates. The results show that magnesium leads to the precipitation of Al8Mg3FeSi6, Mg2Si, and Al5Mg8Cu2Si6 intermetallics. With a strontium addition, dissolution of a large proportion of the needle-like β-Al5FeSi intermetallic in the aluminum matrix takes place; no transformation of this phase into any other intermetallics (including the Al15(Fe,Mn)3Si2 phase) is observed. When both Mg and Sr are added, the diminution of the β-Al5FeSi phase is enhanced, through both its dissolution in the aluminum matrix as well as its transformation into Al8Mg3FeSi6. The reactions and phases obtained have been analyzed using thermal analysis, optical microscopy, image analysis, and electron microprobe analysis (EMPA) coupled with energydispersive X-ray (EDX) analysis.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
G.K. Sigworth, S. Shivkumar, and D. Apelian: AFS Trans., 1989, vol. 97, pp. 811–24.
L. Backerud, G. Chai, and J. Tamminen: Solidification Characteristics of Aluminum Alloys, Vol. 2: Foundry Alloys, AFS/Skanaluminium, Des Plaines, IL, 1990, pp. 71–229.
A.M. Samuel, J. Gauthier, and F.H. Samuel: Metall. Mater. Trans. A, 1996, vol. 27A, pp. 1785–98.
S. Murali, K.S. Raman, and K.S.S. Murthy: Mater. Characterization, 1994, vol. 33, pp. 99–112.
J. Gobrecht: Giesserei, 1976, vol. 63, pp. 558–61.
L.R. Morris and F.B. Miners: U.S. Patent No. 3, 926, 690, 1975.
M.H. Mulazimoglu, A. Zaluska, J.E. Gruzleski, and F. Paray: Metall. Mater. Trans. A, 1996, vol. 27A, pp. 929–36.
F.H. Samuel and A.M. Samuel: Proc. Int. Symp. on Light Metals 1997, 36th Annual Conference of Metallurgists of CIM, Sudbury, ON, Aug. 17–20, 1997, pp. 425–37.
A. Pennors, A.M. Samuel, F.H. Samuel, and H.W. Doty: AFS Trans., 1998, vol 106, paper no. 98–105, in press.
A.M. Samuel, H.W. Doty, and F.H. Samuel: J. Mater. Sci., 1996, vol. 31, pp. 5529–39.
J.E. Gruzleski and B.M. Closset: The Treatment of Liquid Aluminum-Silicon Alloys, American Foundrymen’s Society, Inc., Des Plaines, IL, pp. 25–126.
J. Sakwa: Giesserei-Forschung, 1986, vol. 38, pp. 112–18.
S. Bercovici: “Control of Solidification Structure and Properties of Al-Si Alloys,” Presentation at 45th International Foundry Congress, 1978.
H. de la Sablonniere and F.H. Samuel: Int. J. Cast Met. Res., 1996, vol. 9 (4), pp. 195–211 and pp. 213–25.
P. Ouellet: Master’s Thesis, UQAC, Chicoutimi, 1997.
L.F. Mondolfo: Aluminum Alloys: Structure and Properties, Butterworth and Co., London, 1978, pp. 759–65.
A.M. Samuel and F.H. Samuel: Int. J. Cast Met. Res., 1997, vol. 10, pp. 147–57.
S.C. Flood, P.V. Evans, J.M. Brown, and J. Worth: in Light Metals 1995, J. Evans, ed., TMS, Warrendale, PA, pp. 1127–35.
S.G. Shabestari: Ph.D. Thesis, McGill University, Montreal, 1995.
D.A. Granger: AFS Trans., 1991, vol. 99, pp. 379–83.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Samuel, F.H., Samuel, A.M., Ouellet, P. et al. Effect of Mg and Sr additions on the formation of intermetallics in Al-6 Wt pct Si-3.5 Wt pct Cu-(0.45) to (0.8) Wt pct Fe 319-type alloys. Metall Mater Trans A 29, 2871–2884 (1998). https://doi.org/10.1007/s11661-998-0194-y
Received:
Issue Date:
DOI: https://doi.org/10.1007/s11661-998-0194-y