On the reaction scheme and liquidus surface in the ternary system Al–Si–Ti

Abstract

Abstract The constitution of the ternary system Al–Si–Ti is reinvestigated over the entire composition range using X-ray diffraction, energy dispersive X-ray analysis, differential thermal analysis up to 1500 °C and metallography. The ternary phases τ1 and τ2 are confirmed and their crystal structures and solid state phase equilibria are corroborated. The compositions observed confirm previous literature. The phase τ1 (I41/amd, Zr3Al4Si5-type) melts incongruently at 953 °C < T < 1000 °C into L + τ2 + TiSi2. The phase τ2 (Cmcm, ZrSi2-type) melts incongruently at 1338 °C into L + TiSi + TiSi2. The liquidus surface is characterized by a eutectic trough, which descends monotonically from the pseudobinary maximum emax1 L = βTi + Ti5Si3 at 1540 ± 5 °C through a series of transition reactions and ends in the ternary eutectic L = τ1 + (Si) + (Al) at 573 °C.