Experimental investigation and thermodynamic calculation of the Al-Si-Ti system in Al-rich corner

The phase equilibria in Al-rich corner of the ternary Al-Si-Ti system were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). The ternary phase tau(2) (Ti33Al15Si52, ZrSi2-type) existed stably and equilibrated with TiAl3, fcc(Al) and Si. The DSC results from room temperature to 1000 degrees C indicated that the endothermic peaks corresponded to the quasi-peritectic reaction, liquid -> TiAl3 -> tau(2) + fcc(Al), at 595 degrees C and the eutectic reaction, liquid -> tau(2) + fcc(Al) + Si, at 575 degrees C. Based on the experimental results, a set of self-consistent thermodynamic description of the Al-Si-Ti system was obtained. The calculated isothermal section at 450, 500, 550 and 700 degrees C and the invariant reactions agreed well with the experimental data. (C) 2014 Elsevier B.V.All rights reserved.