Cooling thermal parameters, microstructural spacing and mechanical properties in a directionally solidified hypereutectic Al-Si alloy

Transient directional solidification experiments have been carried out with an Al-15wt. %Si alloy under cooling rates ( ) from 0.2 to 54 K/s. A mixture of globular and fibre-like Si particles within the eutectic is shown to occur for cooling rates ( ) > 9 K/s. The presence of refined globular Si...

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Bibliographic Details
Published in:Philosophical magazine letters 2016-06, Vol.96 (6), p.228-237
Main Authors: Reyes, Rodrigo V., Kakitani, Rafael, Costa, Thiago A., Spinelli, José E., Cheung, Noé, Garcia, Amauri
Format: Article
Language:English
Subjects:
Alloys
Cooling
Cooling rate
cooling thermal parameters
Directional solidification
Elongation
Eutectics
Intermetallic compounds
mechanical properties
Microstructure
Silicon
Solidification
Tensile strength
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Summary:Transient directional solidification experiments have been carried out with an Al-15wt. %Si alloy under cooling rates ( ) from 0.2 to 54 K/s. A mixture of globular and fibre-like Si particles within the eutectic is shown to occur for cooling rates ( ) > 9 K/s. The presence of refined globular Si particles arranging the microstructure either as primary particles or within the eutectic mixture seems to contribute for a combination of high tensile strength (σ u ) and elongation (δ). It is shown by correlations between eutectic (λ Ε ) and secondary dendrite (λ 2 ) spacings and σ u and δ, given by Hall-Petch type formulae that the tensile properties increase significantly with the decrease in these spacings. However, it is shown that for higher ranges of spacings, i.e.: λ Ε −1/2  
ISSN:0950-0839
1362-3036
DOI:10.1080/09500839.2016.1192297