【摘要】 Ti₂AlNb合金因其较高的比强度和高温抗氧化能力，是先进航空发动机热端部件的重要候选材料。但作为金属间化合物材料，其焊接性能是一重要挑战。为了解焊接热循环对合金组织性能的影响规律，使用Gleeble3500热模拟试验机模拟了Ti₂AlNb合金焊缝附近热影响区的热循环，研究了冷却速度对焊接热影响区组织与性能的影响；根据热膨胀-温度曲线，结合不同冷速下合金的显微组织，建立了Ti₂AlNb合金焊接热影响区连续冷却转变（SH-CCT）曲线。结果表明：在快速加热至B2单相区后的连续冷却过程中Ti₂AlNb合金中主要析出相为O相，α₂相的析出量很少。随着冷却速度的增加，析出相的数量逐渐减少、尺寸降低，且α₂相的析出率先被抑制，B2相向O相转变的温度区间缩小。冷却速度低，合金中析出相数量多，强度高，但塑性低。反之，随着冷速的增加，残留B2相增多，合金的塑性得到改善。更多还原

【Abstract】 Ti₂AlNb alloys are promising candidate materials for advanced aviation engine hot end components due to their high specific strength and high-temperature oxidation resistance. But as an intermetallic compound materials, their weldability is a challenging issue. To understand the influence of welding thermal cycling on the microstructure and properties of the alloy, the Gleeble3500 thermal simulation testing machine was used to simulate the thermal cycling in the heat affected zone near the weld of the Ti₂AlNb alloy, and the effect of cooling rate on the microstructure and properties of the welding heat affected zone was studied. Based on the thermal expansion-temperature curves and the microstructure of the alloy at different cooling rates, the simulated HAZ continuous cooling transformation（SH-CCT） curves for the welding heat affected zone of the Ti₂AlNb alloy were established. The results show that during the continuous cooling process after rapid heating to the B2 single-phase zone, the main precipitate in the Ti₂AlNb alloy is O phase, the precipitation amount of α₂ phase is very small. As the cooling rate increases, the number and size of precipitates gradually decrease, and the precipitation of α₂ phase is first suppressed, and the transformation from B2 to O phase is completed within a narrower temperature range. Low cooling rate, large number of precipitates in the alloy, high strength, but low plasticity. On the contrary, with the increase of cooling rate, the residual B2 phase increases, and the plasticity of the alloy is improved.更多还原