Exploration of TiAl₃ Phase Nucleation Mechanism in Al–5Ti–B Master Alloy

In the field of aluminum alloy processing, Al–5Ti–B master alloy stands out as the most widely used grain refiner. The morphology, distribution and quantity of the TiAl₃ phase in the master alloy are critical factors influencing refining effect. In this study, Al–5Ti–B master alloy was prepared by fluoride salt reaction method. The influences of feeding temperature (700–900°C) on the preparation of Al–5Ti–B master alloy were discussed in terms of microstructure characteristics, elemental yields, grain refinement effects and master alloy hardness. The results indicated that with the increasing of feeding temperature, the size of the TiAl₃ phase in the Al–5Ti–B master alloy was gradually decreased until it disappeared, with a gradual increasing of holes. The element recovery rates, refinement effects and master alloy hardness all trended downward. Furthermore, the nucleation mechanism of the TiAl₃ phase was discussed. Based on the impact of feeding temperature on the morphology of the TiAl₃ phase and the analysis of the diffusion movement of Ti element in the melt, coupled with thermodynamic theory, the difficulty of nucleation of the TiAl₃ phase at high temperatures was explained. This study is intended to provide a reference for the control of feeding temperature during the industrial production of high-quality Al–5Ti–B master alloy.