engleski

Thermodynamic stability of AlSi11 alloy microconstituents

Aluminium alloys posses an excellent mechanical, physically-chemical and technological properties which have found an extensive application in the automotive industry. Alloy AlSi_11 belongs to a group of eutectic alloys characterized by high fluidity, low pouring temperature and narrow solidification interval which comprehend to the uniformly distributed eutectic microstructure indicating superior mechanical and technological properties. Study of AlSi11 alloy solidification sequence has been accompanied by calculation of equilibrium phase diagram, and simultaneous thermal analysis, all in correlation to microstructure development. Thermodynamic calculation revealed solidification sequence with corresponded temperatures in equilibrium state. Differential scanning calorimetry enables determination of exact temperatures of phases’ transformations correlated at different cooling rates. Dilatometer thermal analysis defined dimensional changes of AlSi11 alloy. Microstructural examination revealed development of following constituents: primary aluminum (αAl), high temperature intermetallic phases on the iron basis (Al5FeSi and/or Al15(Fe, Mn)3Si2), binary eutectic (αAl+βSi) and secondary eutectic (Mg2Si and Al5Mg8FeSi6) as a last solidifying phases’. Synergy of performed phase diagram calculation, thermodynamic and microstructural investigation enables determination of thermodynamic stability of AlSi11 alloy exposed to different cooling condition, with respect to phase’s evolution.

AlSi11 alloy ; thermodynamic stability ; solidification sequence ; microstructure

Glavni autori: Zdenka Zovko Brodarac, Tamara Holjevac Grgurić