750 ℃高温钛合金是先进高声速飞行器中亟待研发的轻质高强材料，通过超塑性成形制备薄壁部件是该合金的主要应用方向。本工作研究了一种新型高温钛合金Ti750S薄板的超塑性变形行为。结果表明，Ti750S板材在5.00 × 10^-3 s^-1、960 ℃拉伸条件下具有最佳的超塑性性能，拉伸延伸率达120%。板材的平均应变速率敏感因子(m)为0.31，热激活能(Q)为358.338 kJ/mol，建立了Ti750S钛合金的超塑性变形本构方程。超塑性拉伸变形后组织和织构分析表明，片层组织板材在超塑性变形过程中伴随着原始片层组织的动态球化、动态再结晶和织构弱化。板材超塑性变形是片层组织通过动态球化和动态再结晶转化为为等轴组织，然后在位错运动、扩散蠕变和晶粒转动等多种机制协调下发生的晶界滑移过程。

The 750 ℃ high-temperature titanium alloy is a lightweight, high-strength material with potential for the development for advanced hypersonic vehicles, requiring urgent research. The primary prospective application of this alloy is in the fabrication of thin-walled components through superplastic forming. The superplastic deformation behavior of an advanced, high-temperature titanium alloy Ti750S sheet was investigated. The Ti750S sheet exhibited optimal superplastic properties at a strain rate of 5.00 × 10⁻³ s⁻¹ and temperature of 960 ℃, achieving a tensile elongation of 120%. The average strain-rate-sensitivity exponent (m) of the sheet was 0.31 and the calculated thermal activation energy (Q) was 358.338 kJ/mol. Based on these parameters, a constitutive equation for the superplastic deformation of the Ti750S alloy was established. Microstructural and textural analyses after superplastic tensile deformation revealed that the lamellar-structured sheet underwent dynamic spheroidization, dynamic recrystallization, and texture weakening during deformation. The superplastic deformation process involved the transformation of the initial lamellar structure into an equiaxed microstructure via dynamic spheroidization and dynamic recrystallization, followed by grain-boundary sliding, coordinated by dislocation motion, diffusion creep, and grain rotation.