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Dimensional stability of AlSi11 alloy

Alloy AlSi11 belongs to a group of eutectic alloys, which are characterized by high castability, low pouring temperature and narrow solidification interval which makes it suitable for advanced casting technologies. Susceptibility of AlSi11 alloy dimensional stability on extreme temperature condition has been investigated. Thermal stress in material results from thermal expansion incompatibility in materials during the temperature changes. Dilatometer thermal analysis resulted in length extension for l = 111, 29 - 122, 38 µm at 550 °C and reduction l = -11, 86 µm at t = -40 °C and fast regeneration to l-40=17.26 µm. Exposure of the AlSi11 alloy sample to the cyclic thermal load in the temperature range from t  -15 °C to -60 °C resulted in length reduction of l-60=-31.55 µm to l-15=-24.52 µm. Dimensional stability is depended from microconstituents interaction during thermal load. Microstructural investigation reveals that thermal load causes spheroidisation of eutectic Si and recrystallization of primary Al, as well as Mg precipitation. Dimensional i.e. length instability should be considered in extreme application conditions.

AlSi11 alloy ; solidification ; microstructure ; thermal analysis ; dimensional stability

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