The primary phase and liquid local structure during the solidification of Ti–45 pct Al–x pct V (x = 0, 4, 8 and 12, atomic percent) alloys were systemically investigated by combining the drop tube technique and molecular dynamics simulations. In drop tube experiments, the microstructure of Ti–45 pct Al–4 pct V is composed of well-developed α₂ dendrites and its path is liquid → α (hexagonal close packed structure) → α₂. Whereas in Ti–45 pct Al–8 pct V and Ti–45 pct Al–12 pct V alloys, it is composed of lamellar α₂ and its path is liquid → β (body centered cubic structure) → α → α₂. In order to explore the reasons for the primary phase selection, classical molecular dynamics was performed to obtain the liquid local structure. The results reveal that the attractive effect between Al and V atoms is much stronger than Ti-Al and Ti-V atomic pairs in liquid Ti-45% Al-4% V alloy. The total content of 1441+1661 (BCC-type pairs) HA indices is broadly lower than that of 1421+1422 (HCP-type pairs) in liquid Ti-Al-V alloys. The addition of V can enlarge the content of 1441 + 1661 and reduce the content of 1421 + 1422, and it also causes the decline of the fraction of HCP atoms in Ackland–Jones analysis. Moreover, V addition makes the content of 〈0, 0, 12, 0〉 Voronoi polyhedron increase significantly. On the other hand, the total content of 1421 + 1422 goes down with the decrease of cooling rate when the temperature is below the solidification temperature, while the fraction of HCP atoms decreases. Liquid Ti–45 pct Al–4 pct V alloy solidified into crystals with HCP structure at a cooling rate of 10¹⁰ K/s. These results have contributed to the effect of liquid local structure on the primary phase selection during the solidification of Ti–Al based alloys.

通过结合滴管技术和分子动力学模拟，系统地研究了 Ti–45 pct Al– x pct V（x = 0、4、8 和 12，原子百分比）合金凝固过程中的主相和液体局部结构。在滴管实验中，Ti-45 pct Al-4 pct V 的微观结构由发育良好的α ₂枝晶组成，其路径为液态→ α（六方密堆积结构）→ α ₂。而在 Ti–45 pct Al–8 pct V 和 Ti–45 pct Al–12 pct V 合金中，它由层状α ₂组成，其路径是液体 → β（体心立方结构） → α → α₂. 为了探索初级相选择的原因，进行了经典分子动力学以获得液体局部结构。结果表明，在液态 Ti-45% Al-4% V 合金中，Al 和 V 原子之间的吸引作用远强于 Ti-Al 和 Ti-V 原子对。液态Ti-Al-V合金中1441+1661（BCC型对）HA指数的总含量远低于1421+1422（HCP型对）。V的加入可以增大1441+1661的含量，降低1421+1422的含量，同时也会导致Ackland-Jones分析中HCP原子分数的下降。此外，V的添加使<0, 0, 12, 0> Voronoi多面体的含量显着增加。另一方面，当温度低于凝固温度时，随着冷却速度的降低，1421+1422的总含量降低，而HCP原子的比例降低。液态 Ti–45 pct Al–4 pct V 合金在 10 的冷却速率下凝固成 HCP 结构的晶体¹⁰千/秒。这些结果有助于液体局部结构对 Ti-Al 基合金凝固过程中主相选择的影响。