网状结构TiBw/Ti60复合材料的高温塑性变形与强化和氧化机理

Using TiB2 particle and Ti60 alloy particle as the starting materials, TiB whisker reinforced Ti60 alloy composite with a network reinforcement distribution is fabricated by low-energy milling and vacuum reaction hot sintering techniques. The TiB whisker reinforcement is formed by the reaction between TiB2 particle and Ti matrix during hot sintering. Stress-strain behavior and evolution of microstructure and properties of the composite are investigated by hot compression test with different temperature and strain rate, meanwhile, the constitutive equation, processing map and deformation mechanism are obtained. Effects of hot extrusion and hot rolling on microstructure and properties of the composite are researched, and the deformation parameters are optimized. Effects of heat treatment on microstructure and properties of the composite are studied, and the heat treatment parameters are optimized. High temperature tensile property, high temperature creep property and high temperature oxidation properties are tested, and the high temperature strengthening and oxidation mechanisms of the composite are pointed out. Function of the network distributing TiB whisker in the high temperature characteristic of the composite is analyzed. The composite has a similar high temperature properties and higher plastic forming ability compare to the TiAl intermetallic compound. This project will provide theoretical and technical basis for the applications of low-density, high-strength and high thermal resistance alloys using at 700-800℃ in aerospace industry.

以TiB2颗粒和Ti60耐热钛合金颗粒为原料，以TiB2颗粒与基体Ti发生化学反应生成TiB晶须增强相为原理，以具有自主知识产权的低能球磨和真空反应热压烧结技术为方法，制备TiB晶须呈网状分布的Ti60高温钛合金基复合材料。采用高温压缩变形方法研究复合材料在不同变形温度和应变速率下的应力-应变特性与组织性能演化规律，提出本构方程和热加工图，揭示变形机制。研究热挤压和热轧制变形对复合材料组织性能的影响规律和机制，优化热成形工艺参数。研究热处理对复合材料组织与性能影响规律，优化热处理工艺参数。测试复合材料的高温拉伸、高温蠕变和高温抗氧化性能，揭示高温强化与高温氧化机理，阐明网状分布的TiB晶须在复合材料高温特性中的作用机制。该复合材料的耐热性接近TiAl金属间化合物，同时有良好的塑性成形能力。本项目将为航天航空对可在700-800℃使用的轻质、高强、耐热结构材料的需求提供理论支撑和技术保障。

针对航天航空领域对可以在600~800℃使用的轻质、高强、耐热结构材料的迫切需求，制备一种TiB晶须呈空间网状分布的Ti60基复合材料，研究复合材料的热压缩、热挤压、热轧制和热处理相关的理论基础和技术问题，探索复合材料高温强化和高温抗氧化机制，最终实现具有优异室温塑性和高温特性的钛基复合材料及其构件的制备与成形技术。基于前期网状结构钛基复合材料制备及其体系设计经验，采用粒径为110μm的Ti60钛合金粉末与细小TiB2粉为原料，针对Ti60基体合金特点优化了低能球磨工艺与反应热压烧结工艺，成功制备出成功制备了增强体体积分数为0%，1.7%，3.4%，5.1% TiBw/Ti60复合材料。针对烧结态TiBw/Ti60复合材料组织特点，通过高温固溶空冷热处理手段，使得复合材料的室温塑性和强度得到同时提高，进一步优化这种复合材料的力学性能。通过对TiBw/Ti60复合材料进行高温压缩试验，结合变形组织分析，揭示了网状结构TiBw/Ti60复合材料在两相区和β单相区高温变形机制。基于复合材料高温压缩应力应变行为，采用由Sellars和Tegart提出的双曲正弦本构模型来模拟网状结构TiBw/Ti60复合材料的流变应力阶段，建立不同温度区间的本构方程，并根据流变应力数据计算复合材料的变形激活能。结合复合材料高温压缩变形构造的热加工图，对烧结态TiBw/Ti60复合材料进行热挤压变形，揭示了热挤压变形对系列TiBw/Ti60复合材料室温和高温力学性能的影响规律及挤压变形强韧化机制。通过对变形态复合材料进行热处理，揭示了TiBw/Ti60复合材料热处理过程中组织与性能的影响规律及热处理强化机制。通过测试TiBw/Ti60复合材料的高温抗氧化性能，揭示了TiBw/Ti60复合材料氧化动力学规律及网状结构特征对其氧化过程的影响规律。发表学术论文32篇，其中SCI收录28篇，单篇最高影响因子31.083；在国防工业出版社出版《网状结构钛基复合材料》专著1部，参编专著1部；申请国家发明专利9项，已授权6项。培养博士研究生6名，已毕业3名；培养硕士生8名均已毕业。