Bulletin of Materials Science

, Volume 34, Issue 6, pp 1223–1231

Poisoning effect of bismuth on modification behaviour of strontium in LM25 alloy

Article

DOI: 10.1007/s12034-011-0239-5

Cite this article as:
FARAHANY, S., OURDJINI, A., IDRIS, M.H. et al. Bull Mater Sci (2011) 34: 1223. doi:10.1007/s12034-011-0239-5

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.

Keywords

Thermal analysis bismuth modification aluminium alloy 

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Copyright information

© Indian Academy of Sciences 2011

Authors and Affiliations

  1. 1.Materials Engineering DepartmentFaculty of Mechanical Engineering, UTM SkudaiJohorMalaysia

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