| In this paper, the systems of Ti-Al-X (Ti-Al-Nb, Ti-Al-W and Ti-Al-Mo) ternary alloys were established by TT-TiAl database of Thermo-Calc software, and then the thermodynamic phase diagrams of these systems were calculated and verified.The isothermal sections of Ti-Al-Nb, Ti-Al-W and Ti-Al-Mo were calculated from 1000K to the temperature of liquidus. And the accuracy of the calculated phase diagrams were verified by two ways here: One is verifying theα/βandα/γphase equilibriums in different isothermal sections of Ti-Al-Nb, Ti-Al-W and Ti-Al-Mo; the other is verifying the accuracy of three boundary binary systems of Ti-Al-Nb alloys.According to the verification, it was found that the error of thermodynamic calculations of phase diagrams with different X alloys are similar: the calculatedα/γphase equilibriums are precise, whereas the errors ofα/βphase equilibriums are relatively large. For the calculated boundary binary systems of Ti-Al-Nb alloy, the results are precise in the area of low concentration of Nb and Al at high temperature and a little error are presented in other areas of the phase diagrams.The vertical sections of Ti-Al-Nb phase diagram were also calculated. Comparing with Ti-Al binary phase diagram, it was found obviously that: (1) the area ofβphase expands to the high Al of phase diagram as the increasing of Nb containing; (2) the liquidus of vertical sections are higher than Ti-Al binary phase diagram; (3) the phase transitions of vertical sections are more complex.The projection planes of liquid phase of Ti-Al-Nb, Ti-Al-W and Ti-Al-Mo were calculated by calculating the liquid monovariant lines. The three projection planes were compared with each other, and it was found that the component of Al of threeγphase areas are almost same when X constitute is zero. Comparing with Ti-Al binary phase diagram, the areas ofγphase moves to the high Al area in the phase diagrams.
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