Porosity is one of the major defects in aluminum castings and results in a decrease of the mechanical properties of Al-Si alloys. It is induced by two mechanisms: solidification shrinkage and gas segregation. One of the methods for complex evaluation of macro and micro porosity in Al-Si alloys is using the Tatur test technique. This article deals with the evaluation of porosity with the help of Tatur tests for selected Al-Si alloys. These results will be compared with results obtained from the ProCAST simulation software.

A similarity solution for conduction dominated solidification of a dilute binary isomorphous alloy has been developed. The effect solidification due to density change during phase transformation has been highlighted and investigated in detail. The governing equations for solid, liquid and mushy phase has been proposed, taking into account the effect of shrinkage or expansion due to density change during phase change. The thermo-physical properties (thermal conductivity and specific heat), equilibrium temperature and phase fraction are evaluated within the mushy zone using averaging technique. The effect of equilibrium and non-equilibrium solidification is investigated using Lever and Scheil’s rule models respectively. In addition, the effect of boundary and initial temperature on solidification behavior of the alloy is also addressed. It has been observed that the interface (liquidus and solidus) moves faster with increase in density ratio and decrease in boundary and initial temperature. No major changes in temperature distribution and interface position has been observed with variation partition coefficient and microscale behavior model (Lever rule and Scheil’s rule).

Solidification of AlSiFe alloys was studied using a directional solidification facility and the CALPHAD technique was applied to calculate

phase diagrams and to predict occurring phases. The specimens solidified by electromagnetic stirring showed segregation across, and the

measured chemical compositions were transferred into phase diagrams. The ternary phase diagrams presented different solidification paths

caused by segregation in each selected specimen. The property diagrams showed modification in the sequence and precipitation

temperature of the phases. It is proposed in the study to use thermodynamic calculations with Thermo-Calc which enables us to visualize

the mushy zone in directional solidification. 2D maps based on property diagrams show a mushy zone with a liquid channel in the

AlSi7Fe1.0 specimen center, where significant mass fraction (33%) of β-Al5FeSi phases may precipitate before α-Al dendrites form.

Otherwise liquid channel occurred almost empty of β in AlSi7Fe0.5 specimen and completely without β in AlSi9Fe0.2. The property

diagrams revealed also possible formation of α–Al8Fe2Si phases.