700 °C Isothermal Section of the Al-Ti-Si Ternary Phase Diagram

The 700 degrees C isothermal section of the Al-Ti-Si ternary phase diagram has been determined experimentally by means of scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray powder diffraction. Fourteen three-phase regions have been determined experimentally in the isothermal section at 700 degrees C. The ternary phases tau(1) (I4(1)/amd, Zr3Al4Si5-type) and tau(2) (Cmcm, ZrSi2-type) are confirmed in the system at 700 degrees C. The compositions of tau(1) and tau(2) are found as Al6.2-9.3Ti32.4-34.0Si57.5-60.9 and Al10.0-11.6Ti34.2-34.5Si53.9-55.6, respectively. The tau(3) and Ti3Al5 phases are not found in the section. The Ti-rich corner at 700 degrees C shows the presence of three three-phase equilibriums, i.e., (TiAl + Ti3Al + Ti5Si3), (alpha-Ti + Ti3Si + Ti5Si3) and (alpha-Ti + Ti3Al + Ti5Si3). The maximum solubility of Al in Ti5Si3, Ti3Si and alpha-Ti is 6.0, 1.5 and 13.9 at.% at 700 degrees C, respectively. The maximum solubility of Si in L-Al, TiAl3, TiAl2, TiAl, Ti3Al and alpha-Ti is 24.1, 13.6, 1.5, 0.8, 2.3 and 2.3 at.%, respectively.