Influences of Initial Composition and Solid Back Diffusion on the Solidification Path of Al–Fe–Si Alloys

The influence of initial composition and the united solid back diffusion (SBD) effects on the calculated solidification paths (SP) of a series Al–Fe–Si ternary eutectic alloy were analyzed. The calculation programme was coupled with Thermo-Calc to calculate equilibrium for phase diagram information. The calculated results showed that initial compositions and SBD coefficient had important effects on SP of the Al–Fe–Si ternary eutectic alloys. The SP of the five Al–Fe–Si ternary alloys were divided into three categories: \( L \to (L + \beta ) \to (L + \alpha + \beta ) \to (L + \alpha + \beta + \text{Si}) \), \( L \to (L + \alpha ) \to (L + \alpha + \beta ) \to (L + \alpha + \beta + \text{Si}) \), and \( L \to (L + \alpha ) \to (L + \alpha + \text{Si}) \to (L + \alpha + \beta + \text{Si}) \). It was found that the volume fraction of eutectic phase decreases obviously with the increase of the SBD coefficient. Solute distribution coefficients of KFe and KSi in Al–0.08Fe–4.8Si alloy were also calculated and analyzed.