Solidification pathways and phase equilibria in the Mo–Ti–C ternary system

The liquidus surface projection and isothermal section at 1,800°C in the Mo–Ti–C ternary system are examined using arc-melted alloys. A ternary transition peritectic reaction (L + Mo2C → Mo + TiC) takes place during solidification, which is apparently different from the ternary eutectic reaction (L → Mo + TiC + Mo2C) observed in a previous report. Since the composition of the eutectic reaction (L → Mo + TiC) shifts toward the Mo–Ti binary line with increasing Ti concentration, the volume fraction of the Mo phase and the interlamellar spacing of the Mo and TiC phases increase in the eutectic microstructure. At 1,800°C, the TiC phase in equilibrium with the Mo phase can contain more than 28 at% Mo and a Mo/TiC/Mo2C three-phase region exists at around Mo–15Ti–10C.

Thermodynamic Calculation of the Liquidus Projections of the Al-Cu-Fe-Si and Al-Cu-Fe-Mg-Si Multicomponent Systems on Al-Rich Side

The thermodynamic calculations of Al–Cu–Fe–Si quaternary system and Al–Cu–Fe–Mg–Si quinary system were carried out using CALPHAD approach based on the Al–Cu–Fe–Mg–Si thermodynamic database. The liquidus surface projection of Al–Cu–Fe–Si quaternary system at the Al-rich corner was constructed, and then the solidification structures of four Al–Cu–Fe–Si alloys were analyzed by the Gulliver-Scheil solidification simulation. The calculated results were in good agreement with the previous experimental data. The liquidus surface projections of A1–Cu–Fe–Mg–Si quinary system at the region of Al-Cu, Al-Si and Al-Mg were constructed, respectively. The liquidus projection of the multicomponent aluminum alloy system at the Al-rich side was accurately drawn, which could accurately predict the primary phase in the solidification process of the alloy. This work has an important guiding significance for the design of the aluminum alloys.

Thermodynamic Calculation of Liquidus Projection of Multiple Aluminum Alloys

Most aluminum alloys used in industrial manufacturing are multi-component systems. Unfortunately, multi-component systems are still lack of systematic research. The lack of research is especially evident for the liquidus surface projection of the multi-component system where most of the projections are currently drawn by hand. Thermodynamic calculations were performed for the Al–Cu–Mg–Mn quaternary system and the A1–Cu–Fe–Mg–Mn quinary system. The temperatures and compositions of the liquidus invariant reactions in the A1–rich corner for the two systems were calculated and compared with the experimental data. The current work provides a straightforward and accurate expression for the liquidus surface projections of multi-component systems. The expressions will facilitate the understanding of the multi-component alloy systems that are frequently used in industrial applications.