Abstract
Nucleation and growth, temperature measurements and microstructure observations of silicon phase are presented for strontium modified Al–7%Si (LM25) cast alloy treated with bismuth. The results show that addition of bismuth in strontium modified alloys may have a poisoning effect resulting in lost modification of the silicon phase. With increasing Bi/Sr ratio, thermal analysis measurements showed that the eutectic growth temperature increased remarkably to 573°C and recalescence decreased to 0·2°C and the morphology of silicon displayed the same flake-like structure as in the unmodified alloys. Microstructural observation showed that a minimum Bi/Sr ratio of 1·2 which is equivalent to a Sr/Bi ratio of 0·43 is required for effective strontium modification and neutralization of the poisoning effect of bismuth.
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References
Apelian D, Sigworth G K and Whaler K R 1984 AFS Trans. 92 297
Cho J I and Loper C R 2000 AFS Trans. 108 359
Djurdjevic M, Jiang H and Sokolowski J 2001 Mater. Charact. 46 31
El-Hadad S, Samuel A M, Samuel F H, Doty H W and Valtierra S 2004 AFS Trans. 112 141
Elliot R 1983 Eutectic solidification processing (London, UK: Butterworths & Co.)
Emadi D, Whiting L V, Nafisi S and Ghomashchi R 2005 J. Therm. Anal. Calorim. 81 235
Farahany S, Ourdjini A, Idris M H and Thai T 2011 Trans. Nonferrous Met. Soc. China 21 1455
Golbahar B, Samuel F H, Samuel A M, Doty H W and Valtierra S 2007 AFS Trans. 115 07
Gruzleski J E and Closset B M 1990 Treatment of liquid aluminium–silicon alloys (IL, USA: Americans Foundrymen’s Society Inc.)
Hegde S and Narayan Prabhu K 2008 Mater. Sci. 43 3009
Heusler L and Schneider W 2002 Light Met. 2 17
Hosch T, England L G and Napolitano R E 2009 Mater. Sci. 44 4892
Knuutinen A, Nogita K, McDonald S D and Dahle A K 2001 Light Met. 1 229
Loper C R, Seong H G and Cho J I 2001 AFS Trans. 109 1
Lu S Z and Hellawell A 1987 Metall. Trans. A18 1721
Machovec C J, Byczynski G E, Zindel J W and Godlewski L A 2000 AFS Trans. 108 439
Mohamed A M A, Samuel F H, Samuel A M and Doty D H W 2009 Metall. Mater. Trans. A40 240
Nogita K, Knuutinen A, McDonald S D and Dahle A K 2001 Light Met. 1 219
Pan E N, Cherng Y C, Lin C A and Chiou H S 1994 AFS Trans. 102 609
Pillai N P and Anantharaman T R 1968 Trans. Metall. Soc. AIME 24 2025
Qiyang L, Qingchun L and Qifu L 1991 Acta Met. 39 2497
Talbot D E J and Ransley C E 1997 Metall. Mater. Trans. A8 1149
Wang W and Gruzleski J E 1990 AFS Trans. 98 227
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FARAHANY, S., OURDJINI, A., IDRIS, M.H. et al. Poisoning effect of bismuth on modification behaviour of strontium in LM25 alloy. Bull Mater Sci 34, 1223–1231 (2011). https://doi.org/10.1007/s12034-011-0239-5
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DOI: https://doi.org/10.1007/s12034-011-0239-5