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Effect of Sr–Grain Refining–Si Interactions on the Microstructural Characteristics of Al–Si Hypoeutectic Alloys

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Abstract

The present study was performed on A356.2 alloy to explore the link between the effectiveness of different grain refiner practices and strontium (Sr) modification on both the eutectic silicon (Si) particle morphology and the final grain size. To achieve this objective, several types of grain refiners were added to the molten alloy at 750 °C in different concentrations and for various holding times. Strontium was added in the amount of 200 ppm. Thermal analysis combined with microstructure analysis using optical microscopy and electron probe microanalysis was used to assess the results. It was found that Sr has a certain affinity to react with the boron (B) in Al–5%Ti–1%B master alloy which partially reduced the grain refiner effectiveness. The eutectic Si particles maintained a similar degree of modification as in the non-grain refined Sr-modified condition. Al–4%B used with Sr led to the formation of a new intermetallic (SrB6), resulting in a significant decrease in the modification effect of Sr together with an increase in the obtained grain size. This effect increases at higher levels of added Al–4%B. The presence of excess Si leads to a change in the composition of the Al3Ti phase into (Al, Si)2Ti.

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References

  1. Q.T. Fang, D.A. Granger, Porosity formation in modified and unmodified A356 alloy castings. AFS Trans. 97, 989–1000 (1989)

    Google Scholar 

  2. A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Effect of Fe, Sr, P, Ti and undercooling on the precipitation of β-Al5FeSi in A319.2 type alloys. Int. J. Metalcast. (2016). doi:10.1007/s40962-016-0116-5.

  3. Y. Han, A.M. Samuel, F.H. Samuel, H.W. Doty, J. Talamantes, Parameters controlling the tensile properties of non-modified and Sr-modified Al–Si–Cu–Mg 319-type alloys, in Paper 09-078, 113th Metalcasting Congress, April 7–10, Vol. 117 (American Foundry Society, Las Vegas, 2009), pp. 169–186

  4. G.K. Sigworth, M.M. Guzowski, Grain refining of hypoeutectic Al–Si alloys. AFS Trans. 93, 907–912 (1985)

    Google Scholar 

  5. H. Tahiri, A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Effect of Sr–grain refiner–Si interaction on the microstructure characteristics of Al–Si hyper-eutectic alloys. Int. J. Metalcast. (2017). doi:10.1007/s40962-017-0164-5

  6. T. Sritharan, H. Li, Influence of titanium to boron ratio on the ability to grain refine aluminium–silicon alloys. J. Mater. Process. Technol. 63, 585–589 (1977)

    Article  Google Scholar 

  7. S.A. Kori, B.S. Murty, M. Chakraborty, Influence of silicon and magnesium on the grain refinement in aluminium alloys. Mater. Sci. Technol. 15, 986–992 (1999)

    Article  Google Scholar 

  8. H. Liao, G. Sun, Mutual poisoning effect between Sr and B in Al–Si casting alloys. Scr. Mater. 48, 1035–1039 (2003)

    Article  Google Scholar 

  9. L. Lu, A.K. Dahle, Effects of combined additions of Sr and AlTiB grain refiners in hypoeutectic Al–Si foundry alloys. Mater. Sci. Eng. A 435–436, 288–296 (2006)

    Article  Google Scholar 

  10. P.D. Lee, T.C. Lindley, The influence of strontium and TiB2 additions on the formation of porosity in aluminum castings and their effect on final fatigue properties, Foundry Trade Journal, 2004

  11. P.S. Mohanty, F.H. Samuel, J.E. Gruzleski, Studies on addition of inclusions to molten aluminum using a novel technique. Metall. Mater. Trans. B 26B, 103–109 (1995)

    Article  Google Scholar 

  12. Brouchure of KB Alloys, Inc., Strontium-Boron, Combination Grain Refiner and Modifier, Vol. 1, 1999

  13. W. Khalifa, F.H. Samuel, J.E. Gruzleski, Inclusion additions to molten aluminum alloys using the gas injection technique: process and analysis, in Transactions of the American Foundry Society: volume 113; 109th Metalcasting Congress, April 16–19, 2005: CastExpo’05, St. Louis, Missouri. 2005 (American Foundry Society: CastExpo’05, St. Louis), pp. 207–224

  14. L. Backerud, M. Johnsson, The relative importance of nucleation and growth mechanisms to control grain size in various aluminum alloys, in Light Metals 1996: Proceedings of the Technical Sessions Presented by the TMS Light Metals Committee at the 125th TMS Annual Meeting, edited by W. Hale, Anaheim, California, February 4–8, 1996 (The Minerals, Metals and Materials Society, Warrendale, PA, 1996), pp. 679–685

  15. P. Cooper, A. Hardman, Ed. Burhop, Light Metals 2003 (TMS, Warrendale, 2003), pp. 1–6

    Google Scholar 

  16. D.B. Dusenbery, Living at Micro Scale (Harvard University Press, Cambridge, 2009). (ISBN 978-0-674-03116-6)

    Google Scholar 

  17. H. Li, T. Sritharan, Y.M. Lam, N.Y. Leng, Effects of processing parameters on the performance of Al grain refinement master alloys Al–Ti and Al–B in small ingots. J. Mater. Process. Technol. 66, 253–257 (1997)

    Article  Google Scholar 

  18. E. Samuel, B. Golbahar, A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Effect of grain refiner on the tensile and impact properties of Al–Si–Mg cast alloys. Mater. Des. 56, 468–479 (2014)

    Article  Google Scholar 

  19. B. Golbahar, E. Samuel, A.M. Samuel, H.W. Doty, F.H. Samuel, On thermal analysis, macrostructure and microstructure of grain refined Al–Si–Mg cast alloys: role of Sr addition. Int. J. Cast Met. Res. 27(5), 257–266 (2014)

    Article  Google Scholar 

  20. A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Influence of oxides on porosity formation in Sr-treated alloys. Int. J. Metalcast. (2016). doi:10.1007/s40962-016-0118-3

  21. A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Effect of grain refining and Sr-modification interactions on the impact toughness of Al–Si–Mg cast alloys. Mater. Des. 56, 264–273 (2014)

    Article  Google Scholar 

  22. H.R. Ammar, A.M. Samuel, F.H. Samuel, E.A. Simielli, J.C. Lin, G.K. Sigworth, Effects of Mg-addition, Sr-modification and solidification rate on the tensile properties and quality index of 359 type Al–Si–Mg casting alloys, in Transactions of the American Foundry Society, 115th Metalcasting Congress, April 5–8, Vol. 119 (Schaumburg, 2011), pp. 67–82

  23. J.G. Li, B.Q. Zhang, L. Wang, W.Y. Yang, H.T. Ma, Combined effect and its mechanism of Al–3wt.%Ti–4wt.%B and Al–10wt.%Sr master alloy on microstructures of Al–Si–Cu alloy. Mater. Sci. Eng. A328, 169–176 (2002)

    Article  Google Scholar 

  24. S. Nafisi, Effects of grain refining and modification on the microstructural evolution of semi-solid 356 Alloy, Ph.D. Thesis, Université du Québec à Chicoutimi, Chicoutimi, 2006, p. 358

  25. The treatment of liquid Al–Si alloys, J.E. Gruzleski and B.M. Closset, American Foundrymen’s Society Inc., 1990

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Acknowledgements

The authors would like to thank Amal Samuel and Hicham Farid for enhancing the quality of the images and drawings presented in this article and Dr. A.M. Samuel for editing the manuscript.

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Authors and Affiliations

  1. Département des Sciences appliquées, Université du Québec à Chicoutimi Québec, Chicoutimi, Canada

    H. Tahiri, S. S. Mohamed & F. H. Samuel

  2. General Motors Materials Engineering, Pontiac, MI, USA

    H. W. Doty

  3. Nemak, S.A., Garza Garcia, N.L., Mexico

    S. Valtierra

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  1. H. Tahiri
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  2. S. S. Mohamed
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  3. H. W. Doty
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  4. S. Valtierra
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  5. F. H. Samuel
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Correspondence to F. H. Samuel.

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Tahiri, H., Mohamed, S.S., Doty, H.W. et al. Effect of Sr–Grain Refining–Si Interactions on the Microstructural Characteristics of Al–Si Hypoeutectic Alloys. Inter Metalcast 12, 343–361 (2018). https://doi.org/10.1007/s40962-017-0169-0

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