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

Publication date: 5 February 2017
Source:Materials & Design, Volume 115
Author(s): Qian Li, Zi-Wei Chen, Qun Luo, Bao-Wei Li
Vanadium was added into Al-Ti based alloys to improve the intermediate temperature ductility and refine the grains. However, the change of phase relations and phase transitions resulted from the V addition has not been fully understood. In this study, the phase equilibria in the Al-rich corner of Al-Ti-V system were investigated using X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer and differential scanning calorimeter. To validate the phase relations, five Al-rich key alloys were prepared and annealed at 600°C and 700°C for 360h respectively. The results indicated that two three-phase regions and three two-phase regions exist in the Al-rich corner at 600°C. And one three-phase region and four two-phase regions are stable at 700°C. The EDS results showed that the solubility of V in TiAl3 can vary from 2.8at.% to 27.0at.%, which results in a solid solution phase (Ti, V)Al3. Based on the isothermal phase equilibria at 600°C and 700°C and the invariant reactions determined in this work, the model parameters of (Ti, V)Al3 were optimized and a new thermodynamic description of Al-Ti-V system was obtained. Comparing the calculated results with the experimental data, a good agreement was reached.

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