网状结构TiBw/TC4复合材料高温塑性变形行为与机理

TiB whiskers reinforced TC4 matrix (TiBw/TC4) composites with a three-dimensional quasi-continuous network distribution of reinforcement exhibited a superior combination of strength and ductility at room temperature and high temperatures. Moreover, different superior mechanical properties (high strength, high ductility, superior combination of strength and toughness or high temperature durability) can be obtained by controlling different parameters of the network structure, such as local volume fraction, overall volume fraction and network size. These advantages render them extensive application potentials. The hot compressive deformation and superplastic tensile deformation with different conditions (temperature, strain rate and deformation degree) will be performed on TiBw/TC4 composites with different structure parameters in order to investigate behaviors of stress and strain of the composites under different deformation kinds (compression or tension). Different constitutive equations and processing maps for hot compressive deformation and hot tensile deformation will be constructed based on stress and strain values obtained from the stress-strain curves. By means of their three-dimensional network distribution of reinforcement, the effects of deformation kinds, network structure parameters and deformation conditions on the microstructure evolution and mechanical property evolution of TiBw/TC4 composites can be clarified, and then the plastic deformation mechanisms of the composites can be thoroughly revealed. Certainly, the optimal deformation conditions can be drawn by analyzing the testing results. The final aim is to construct theory and experiment foundations of plastic deformation processing and superplastic forming for network structured TiBw/TC4 composites with different parameters, and then provide theory support and technique guarantee for their extensive applications in aerospace industry.

增强相呈三维准连续网状分布的TiB晶须增强TC4基(TiBw/TC4)复合材料表现出优异的综合性能(室温与高温的强度与塑性)，并且调控网状结构参数(局部与整体增强相含量、网状尺寸)可以获得不同性能特点(高强度、高塑性、高强韧性、高耐热性)，具有较大的应用潜力。进一步采用高温压缩与超塑性拉伸的方法，研究不同网状结构参数TiBw/TC4复合材料在不同变形方式(压缩与拉伸)及不同变形条件(温度、应变速率、变形量)下的应力-应变行为，建立其高温压缩与高温拉伸本构方程及热加工图，借助其增强相三维网状分布特征，阐明网状结构参数、变形方式、变形条件对TiBw/TC4复合材料组织与性能演变的影响规律，全面揭示其塑性变形机理，并优化其高温压缩与超塑性拉伸最佳变形条件。为不同网状结构参数TiBw/TC4复合材料塑性变形加工与超塑性成形建立理论与实验基础，为其在航空航天上广泛应用提供可靠的理论支撑和技术保障。

网状结构钛基复合材料具有优异的综合性能，并且调控网状结构参数可以获得不同性能特点，具有广泛的应用前景。为了满足航天航空对轻质耐热高强韧网状结构钛基复合材料及其成形技术的迫切需求，本项目以网状结构TiBw/TC4复合材料为例，采用高温压缩与超塑性拉伸的方法，研究了其变形行为与机理。采用不同尺寸的TC4球形粉与不同比例的TiB2细粉为原料，成功制备出不同网状结构参数的TiBw/TC4复合材料。通过对不同网状结构参数TiBw/TC4复合材料进行高温压缩变形试验，揭示了网状结构参数与变形条件对其应力-应变行为的影响规律，并建立了TiBw/TC4复合材料的高温压缩热变形本构方程。建立了不同网状结构参数TiBw/TC4复合材料在不同应变量及应变速率下的高温压缩热加工图，并将热变形工艺同变形后组织相对应，实现了对材料热变形性能及变形后组织的可预测、可调控。使用显微硬度计对不同温度及变形速率下热压缩变形后的TiBw/TC4复合材料硬度进行了测试以预测热变形试样性能。在优化的工艺参数下制备了大尺寸等温锻造TiBw/TC4复合材料，并对材料各部位的力学性能进行了测试，阐明了变形条件对其组织与性能的影响规律。对TiBw/TC4复合材料在900℃~1000℃温度范围内，0.0005~0.01s-1应变速率范围内进行了高温超塑性拉伸试验，并观察了超塑性变形后试样组织，阐明了TiBw/TC4复合材料的超塑性变形行为、变形机制与组织演变规律。建立了网状结构钛基复合材料热变形与热处理改性新方法，实现了组织与性能进一步调控，满足了航天航空飞行器减重提速的迫切需求，研制出的某新型导弹发动机钛基复合材料气动格栅(Φ580mm)，已成功通过了地面例试。发表学术论文37篇，其中SCI收录34篇，单篇最高影响因子23.75；在Springer与国防工业出版社出版专著2部，参编专著2部；已授权国家发明专利10项。培养博士研究生6名，已毕业2名；培养硕士生8名均已毕业。