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

Abstract

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 τ2 (Ti33Al15Si52, ZrSi2-type) existed stably and equilibrated with TiAl3, fcc(Al) and Si. The DSC results from room temperature to 1000°C indicated that the endothermic peaks corresponded to the quasi-peritectic reaction, liquid+TiAl3→τ2+fcc(Al), at 595°C and the eutectic reaction, liquid→τ2+fcc(Al)+Si, at 575°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°C and the invariant reactions agreed well with the experimental data.