Abstract
Thermal and microscopy analyses were carried out to investigate the interaction of Sr modification with Ca and P trace elements in high-purity and commercial-purity Al–5Si–1Cu–Mg alloys. The results show how the addition of Sr to commercial-purity alloy induces significant changes in the nucleation and growth temperatures of eutectic Si since pre-eutectic Al2Si2(CaSr) intermetallics tend to poison AlP particles, making them inactive as nucleation sites for eutectic Si. In contrast, the addition of Sr to high-purity alloy shows no apparent influence on the characteristic temperatures of Al–Si eutectic reaction, even though the microstructural investigations reveal flake-to-fibrous transition in the eutectic Si structure. This indicates that the eutectic growth temperature, commonly used to predict eutectic modification level, is not a key feature of Sr modification, but it is indirectly caused due to the presence of additional impurities in commercial-purity alloys which affect the nucleation kinetics of eutectic Si.
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References
Ludwig TH. Trace elements in Al–Si foundry alloys. Trondheim: University of Science and Technology (NTNU); 2013.
Tański T, Labisz K, Krupińska B, Krupiński M, Król M, Maniara R, Borek W. Analysis of crystallization kinetics of cast aluminum–silicon alloy. J Therm Anal Calorim. 2016;123:63–74.
Mahfoud M, Prasada Rao AK, Emadi D. The role of thermal analysis in detecting impurity levels during aluminum recycling. J Therm Anal Calorim. 2010;100:847–51.
EN 1706:2010. Aluminium and aluminium alloys—castings—chemical composition and mechanical properties.
Gruzleski J, Closset B. The treatment of liquid aluminum–silicon alloys. Schaumburg: American Foundrymen’s Society; 1990.
Knuutinen A, Nogita K, McDonald SD, Dahle AK. Modification of Al–Si alloys with Ba, Ca, Y and Yb. J Light Met. 2001;1:229–40.
Kobayashi T, Kim HJ, Niinomi M. Effect of calcium on mechanical properties of recycled aluminium casting alloys. Mater Sci Technol. 1997;13:497–502.
Nogita K, Knuutinen A, McDonald SD, Dahle AK. Mechanisms of eutectic solidification in Al–Si alloys modified with Ba, Ca, Y and Yb. J Light Met. 2001;1:219–28.
Ludwig TH, Schaffer PL, Arnberg L. Influence of some trace elements on solidification path and microstructure of Al–Si foundry alloys. Metall Mater Trans A. 2013;44:3783–96.
Knuutinen A, Nogita K, McDonald SD, Dahle AK. Porosity in aluminium alloy A356 modified with Ba, Ca, Y and Yb. J Light Met. 2001;1:241–9.
Dai HS, Liu XF. Optimal holding temperatures and phosphorus additions for primary silicon refinement in Al—high Si alloys. Mater Sci Technol. 2009;25:1183–8.
Ludwig TH, Schaffer PL, Arnberg L. Influence of phosphorus on the nucleation of eutectic silicon in Al–Si alloys. Metall Mater Trans A. 2013;44:5796–805.
Al-Helal K, Wang Y, Stone I, Fan Z. Effect of Ca level on the formation of silicon phases during solidification of hypereutectic Al–Si alloys. Mater Sci Forum. 2013;765:117–22.
Qiao J, Liu X, Liu X, Bian X. Relationship between microstructures and contents of Ca/P in near-eutectic Al–Si piston alloys. Mater Lett. 2005;59:1790–4.
Ludwig TH, Schonhovd Dæhlen E, Schaffer PL, Arnberg L. The effect of Ca and P interaction on the Al–Si eutectic in a hypoeutectic Al–Si alloy. J Alloys Compd. 2014;586:180–90.
Farahany S, Idris MH, Ourdjini A, Faris F, Ghandvar H. Evaluation of the effect of grain refiners on the solidification characteristics of an Sr-modified ADC12 die-casting alloy by cooling curve thermal analysis. J Therm Anal Calorim. 2015;119:1593–601.
Farahany S, Ourdjini A, Idris MH, Shabestari SG. Computer-aided cooling curve thermal analysis of near eutectic Al–Si–Cu–Fe alloy: effect of silicon modifier/refiner and solidification conditions on the nucleation and growth of dendrites. J Therm Anal Calorim. 2013;114:705–17.
Farahany S, Ourdjini A, Idris MH. The usage of computer-aided cooling curve thermal analysis to optimise eutectic refiner and modifier in Al–Si alloys. J Therm Anal Calorim. 2012;109:105–11.
Samuel A, Doty H, Gallardo S, Samuel F. The effect of Bi–Sr and Ca–Sr interactions on the microstructure and tensile properties of Al–Si-based alloys. Mater. 2016;9:1–13.
Mrówka-Nowotnik G, Sieniawski J. Microstructure and mechanical properties of C355.0 cast aluminium alloy. Arch Mater Sci Eng. 2011;47:85–94.
Djurdjevic MB, Vicario I, Huber G. Review of thermal analysis applications in aluminium casting plants. Rev Metal. 2014;50:1–12.
Tamminen J. Thermal analysis for investigation of solidification mechanisms in metals and alloys. Stockholm: University of Stockholm; 1988.
Dahle AK, Nogita K, McDonald SD, Dinnis C, Lu L. Eutectic modification and microstructure development in Al–Si Alloys. Mater Sci Eng A. 2005;413:243–8.
Dahle AK, Nogita K, Zindel JW, McDonald SD, Hogan LM. Eutectic nucleation and growth in hypoeutectic Al–Si alloys at different strontium levels. Metall Mater Trans A. 2001;32:949–60.
McDonald SD, Nogita K, Dahle AK. Eutectic nucleation in Al–Si alloys. Acta Mater. 2004;52:4273–80.
Eiken J, Apel M, Liang S-M, Schmid-Fetzer R. Impact of P and Sr on solidification sequence and morphology of hypoeutectic Al–Si alloys: combined thermodynamic computation and phase-field simulation. Acta Mater. 2015;98:152–63.
Cho YH, Lee HC, Oh KH, Dahle AK. Effect of strontium and phosphorus on eutectic Al–Si nucleation and formation of β-Al5FeSi in hypoeutectic Al–Si foundry alloys. Metall Mater Trans A. 2008;39:2435–48.
Zamani M, Seifeddine S. Assessment of modification level in EN AC-46000 aluminum casting alloys using thermal analysis and microscopic evaluation. In: Hyland M, editor. Light metals 2015. Cham: Springer; 2015. p. 955–60.
Malekan M, Dayani D, Mir A. Thermal analysis study on the simultaneous grain refinement and modification of 380.3 aluminum alloy. J Therm Anal Calorim. 2014;115:393–9.
Malekan M, Shabestari SG. Computer-aided cooling curve thermal analysis used to predict the quality of aluminum alloys. J Therm Anal Calorim. 2011;103:453–8.
Rakhmonov J, Timelli G, Bonollo F. Influence of melt superheat, Sr modifier, and Al–5Ti–1B grain refiner on microstructural evolution of secondary Al–Si–Cu alloys. Metall Mater Trans A. 2016;47:5510–21.
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The authors would like to acknowledge Dr. A. Fabrizi for his precious work to perform experiments and characterizations.
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Rakhmonov, J., Timelli, G. & Basso, G. Interaction of Ca, P trace elements and Sr modification in AlSi5Cu1Mg alloys. J Therm Anal Calorim 133, 123–133 (2018). https://doi.org/10.1007/s10973-018-7111-4
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DOI: https://doi.org/10.1007/s10973-018-7111-4