Solidification Path Calculation of ternary Al-Cu-Mg alloys in Al rich corner

ABSTRACT The liquid solidification paths of ternary eutectic and quasiperitectic Al-Cu-Mg alloys in Al-rich corner were calculated using an extended microsegregation model. The user’s programs were coupled with CALPHAD software for calculating the thermodynamic data of the investigated alloys. The influences of initial composition, average solidification rate, assumption of dendrite morphology, diffusion coefficient and the united solid back diffusion (SBD) parameter Фn on solidification paths were investigated. It was found that differences of the above parameters could greatly affect the liquid solidification path, types and quantities of the precipitated phases, and concentration of solutes in liquid phase. Solidification experiments were carried out with four Al-Cu-Mg alloys to verify the accuracy of the calculation, and reasonable agreements were obtained between the predicted solidification paths and the experiment results.