增强体对钛基复合材料离心铸造行为的影响机制

Titanium matrix composites (TMCs) have been extensively applied in areas such as aerospace and advanced weapon systems, because of their high specific strength, specific modulus and mechanical properties. The complex structure components are usually adopted in aerospace area. The near-net-shape casting technique is a low-cost and high yield potential method in complex structure components forming. With the reinforcements increasing, the fluidity of TMCs decreases, the mechanical property changes become complex. Numerical simulation and experiments will be employed to investigate the process of centrifugal casting of TMCs. The purpose of this project is to investigate the effect of reinforcement’s type and content on fluidity and solidification mechanism of TMCs. The quantitative relationships between fluidity length and reinforcement’s type and content in TMCs will be established. The effect of reinforcement’s type and content on flow characteristics、temperature field、distribution characteristics of stress and defects in process of centrifugal casting will be investigated. The effect of centrifugal rotational speed on the trajectory path and distribution characteristics of reinforcement will be analyzed. The control mechanism of reinforcement’s type、size、distribution characteristics and mechanical properties of TMCs in the process of centrifugal casting will be established. And theoretical guidance will be provided to develop titanium matrix composites applied in the field of precision casting, and improve the comprehensive performance of TMCs precision casting.

钛基复合材料既保持了钛的优良性质又具有比钛更高的比强度和比模量，在航空航天领域应用越来越广。而在航空航天领域常采用一些结构复杂的构件，精密铸造技术可以实现复杂结构零件的近终成形，显著提高材料的利用率，降低制造成本。但增强体的引入使钛基复合材料流动性下降，铸件性能调控更加复杂。本项目采用数值模拟与实验相结合的方法，研究增强体的种类与含量对材料流动性影响规律及流动停止机制，建立增强体种类、含量与钛基复合材料最大流动线长度之间的量化关系。探索离心铸造过程中增强体种类和含量对铸造过程中流场、温度场、应力场分布、缺陷形成与分布的影响机制以及在离心力的作用下增强体的析出、运动轨迹和分布规律，实现离心铸造过程中增强体形状、尺寸及分布可控的同时使铸件具有优良的力学性能，并为进一步拓展钛基复合材料在精密铸造成形领域的应用，提高钛基复合材料精密铸件的综合性能提供理论指导。

研究钛基复合材料精密铸造对满足航空航天等国家重大需求具有重要的科学意义和使用价值。然而，在增强体的加入，钛基复合材料的钛基复合材料流动性下降，提高钛基复合材料的精密铸造难度。本项目设计了4种钛基复合材料，采用数值模拟与实验相结合的方法，研究了浇铸温度，浇铸速度以及增强体对钛基复合材料流动性的影响规律，优化出了最佳浇铸工艺，得出了增强体种类、含量与钛基复合材料最大流动线长度之间的量化关。采用数值模拟的方法，探明了离心速度与对铸造过程中流场、温度场、应力场分布、缺陷形成与分布的影响规律，同时发现了离心力的作用下增强体的运动轨迹和分布规律，实现了离心铸造过程中增强体形状、尺寸及分布可控的同时使铸件具有优良的力学性能，为提高钛基复合材料精密铸件的综合性能提供理论指导。铸造出了性能优良的钛基复合材料精密铸件，并得到了实际应用。