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Effect of Cooling Rate and Fe/Mn Weight Ratio on Volume Fractions of α-AlFeSi and β-AlFeSi Phases in Al-7.3Si-3.5Cu Alloy
Ist Teil von
Metals and materials international, 2008-06, Vol.14 (3), p.307-314
Ort / Verlag
대한금속재료학회
Erscheinungsjahr
2008
Link zum Volltext
Quelle
springer (창간호~2014)
Beschreibungen/Notizen
The crystallization behavior of iron intermetallic compounds in Al-7.3Si-3.5Cu alloy was investigated using thermal analysis, metallography, and a thermodynamic simulation performed with the Scheil module of ThermoCalc(R). We observed that β-AlFeSi disappeared when both high (>3.5℃/s) and low cooling rates (<0.1℃/s) were used. The elimination of β-AlFeSi at low cooling rates may be attributable to a decrease in the magnitude of microsegregation associated with low cooling rates. The disappearance of β-AlFeSi at high cooling rates may be related to growth difficulties when this phase precipitates during solidification of eutectic Al-Si: β-AlFeSi precipitation approaches the solidification onset of eutectic Al-Si when the cooling rate is increased. Moreover, the cooling rate at which the β-AlFeSi phase is suppressed should depend on the chemical composition of the alloy. According to thermodynamic simulations, the alloy composition determines the precipitation onset temperature of both β-AlFeSi (Tβ) and eutectic Al-Si (T(eut)). The cooling rate at which the β-AlFeSi phase disappears may be even higher as the difference between Tβ and T(eut) increases.