Heterogeneous nucleation of solidification of Si in Al-Si and Al-Si-P alloys

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(94)00480-6· OSTI ID:100618

Ho, C R; Cantor, B ^[1]

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1. Oxford Univ. (United Kingdom)

Heterogeneous nucleation of solidification in melt spun Al-Si and Al-Si-P has been studied using differential scanning calorimetry, and transmission, scanning transmission and high resolution electron microscopies. The microstructures of the heat treated melt spun alloys all consist of an Al matrix, Al-Si eutectic distributed along the Al grain boundaries, and Si embedded in the Al matrix. The Si microstructure depends on the level of P: coarse faceted Si particles are nucleated by AlP particles in Al-Si containing 2 ppm P and Al-Si-P containing 35 ppm P whereas eutectic droplets of fine Si particles are nucleated by the surrounding Al matrix at a high undercooling in Al-Si containing 0.25 ppm P. The Si nucleation onset temperature remains approximately constant while the peak and end temperatures both decrease with increasing cooling rate, in agreement with classical nucleation theory. Kinetic analysis, using the spherical cap model gives contact angles of 10{degree}, 43{degree} and 10{degree} for Si nucleation in low and high purity Al-Si and Al-Si-P respectively.

• OSTI ID: 100618
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 8 Vol. 43; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CALORIMETRY
EUTECTICS
GRAIN BOUNDARIES
IMPURITIES
LIQUID METALS
MICROSTRUCTURE
PARTICULATES
PHOSPHORUS
SAMPLE PREPARATION
SILICON ALLOYS
SOLIDIFICATION
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY