Solidification Simulation of Equiaxed Grains in Al - Si Eutectic Alloys

Mahallawy, Nahed El; Hanafi, Mohamed Ahmed Taha; El-Kharbotly, Amin K.; Castaldini, A.; Svenson, I.

doi:10.4028/www.scientific.net/msf.217-222.347

Cited by 4 publications

(2 citation statements)

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“…[18] Despite these limitations, similar growth models are commonly used in microscopic modeling, [21,22,29] and they are likely to be accurate within an order of magnitude. A quantitative interpretation of Figures 12 and 13 requires caution, although it is of interest to investigate how well the model predictions compare with microstructural observations.…”

Section: Discussionmentioning

confidence: 99%

“…[20] Correspondingly, the growth velocity of a eutectic grain will be highest at the beginning and end of solidification and pass through a minimum sometime during solidification. The actual interface velocity during eutectic solidification can be calculated by assuming spherical growth and applying classical eutectic growth theory: [21,22] [1]…”

Section: Discussionmentioning

confidence: 99%

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Eutectic grains in unmodified and strontium-modified hypoeutectic aluminum-silicon alloys

McDonald

Dahle

Taylor

et al. 2004

Metall Mater Trans A

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Additions of strontium to hypoeutectic aluminum-silicon alloys modify the morphology of the eutectic silicon phase from a coarse platelike structure to a fine fibrous structure. Thermal analysis, interrupted solidification, and microstructural examination of sand castings in this work revealed that, in addition to a change in silicon morphology, modification with strontium also causes an increase in the size of eutectic grains. The eutectic grain size increases because fewer grains nucleate, possibly due to poisoning of the phosphorus-based nucleants, that are active in the unmodified alloy. A simple growth model is developed to estimate the interface velocity during solidification of a eutectic grain. The model confirms, independent of microstructural observations, that the addition of 100 ppm strontium increases the eutectic grain size by at least an order of magnitude compared with the equivalent unmodified alloy. The model predicts that the growth velocity varies significantly during eutectic growth. At low strontium levels, these variations may be sufficient to cause transitions between flake and fibrous silicon morphologies depending on the casting conditions. The model can be used to rationally interpret the eutectic grain structure and silicon morphology of fully solidified aluminum-silicon castings and, when coupled with reliable thermal data, can be used to estimate the eutectic grain size.

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Section: Discussionmentioning

confidence: 99%