The U–Ti binary system was investigated via experimental measurements and thermodynamic modeling. In order to clarify the disputed phase equilibria of the U–Ti system, 11 alloys with different contents of Ti were prepared by arc melting. The investigated Ti content covers the U-rich portion within the composition range from 1 at.% Ti to 33.3 at.% Ti. All samples were annealed at the temperatures of 640, 720 and 730 °C, and then analyzed by optical microscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and differential scanning calorimeter. The phase equilibria associated with γ(U,Ti), αU, βU, and δ-U₂Ti were experimentally determined in detail. The reaction temperature and composition of the invariant reaction γ(U,Ti) → βU + δ-U₂Ti were precisely determined, and the invariant reaction temperature of the reaction βU→ αU + δ-U₂Ti was updated. The solid solubility of Ti in αU at low temperatures was also revised by experiments. The temperature and the enthalpy of transition δ-U₂Ti to γ(U,Ti) were newly measured by the differential scanning calorimeter. Finally, a set of self-consistent thermodynamic parameters were obtained by taking into account the present experimental findings and reliable literature data using CALPHAD (Calculation of phase diagrams) technique, and all calculated results are in good agreement with the experimental ones.

通过实验测量和热力学建模研究了 U-Ti 二元系统。为了澄清 U-Ti 体系中存在争议的相平衡，通过电弧熔炼制备了 11 种不同 Ti 含量的合金。研究的 Ti 含量涵盖了成分范围从 1 at.% Ti 到 33.3 at.% Ti 的富 U 部分。所有样品均在 640、720 和 730°C 的温度下退火，然后通过光学显微镜、X 射线衍射、扫描电子显微镜、能量色散 X 射线光谱和差示扫描量热仪进行分析。通过实验详细确定了与 γ(U,Ti)、αU、βU 和 δ-U ₂ Ti相关的相平衡。不变反应的反应温度和成分γ(U,Ti) → βU + δ-U ₂精确测定Ti，更新反应βU→αU+δ-U ₂ Ti的不变反应温度。Ti在低温下在αU中的固溶度也通过实验修正。用差示扫描量热仪新测量了温度和从δ-U ₂ Ti 到γ(U,Ti)的转变焓。最后，结合现有的实验结果和可靠的文献数据，采用CALPHAD（相图计算）技术得到了一组自洽的热力学参数，所有计算结果与实验结果吻合良好。