累积叠轧制备Ti/Ni多层形状记忆复合材料及其性能调控基础研究

Ti/Ni multilayer shape memory composite materials can realize the miniaturization and intelligence of the control system because of the fast response speed and high sensitivity. It is a hot point of current researching on shape memory alloy. However, the composition, microstructure, interface structure and phases composition of Ti/Ni multilayer shape memory composites have important influence on material mechanics and physical properties. It is the key to the reliability and stability of the material in using process. How to optimize the relationship between them, and then controlling the properties of Ti/Ni multilayer shape memory composite materials, further research is needed. For its application has great significance. The purpose of this project is to produce Ti/Ni multilayer structure shape memory composite materials with pure Ti and pure Ni sheet as raw materials by accumulative roll bonding and solid phase thermal diffusion. Using thermal compression and finite element simulation, and combining with the analysis of thermodynamics and kinetics, the evolution of structure, deformation behavior, deformation coordination, interface reformatting and its mechanism of action in accumulative roll bonding processes. And the diffusion behavior, diffusion reaction, formation and development of intermetallic compounds in high-energy state interface are are discussed, and the rolling composite model and the interface diffusion model are established. The relatedness between preparation processes, microstructure, and deformation coordinated property, interface structure, phases’ composition and properties of Ti/Ni multilayer structure shape memory composite materials is revealed. And the theoretical basis and technical support are provided for the preparation, controlling properties and application of Ti/Ni multilayer shape memory composites.

Ti/Ni多层形状记忆复合材料因响应速度快和灵敏度高，可实现控制系统微型化、智能化，是当前研究的热点。但材料的组分比例、组织、界面结构和相组成等对力学和物理性能有重要影响，是服役过程中性能可靠和稳定的关键，如何优化它们之间的关系，进而调控性能，还需进一步深入研究。本项目以钛、镍板为原料，采用累积叠轧和热扩散制备Ti/Ni多层形状记忆复合材料。利用热模拟和有限元模拟，结合热力学和动力学计算分析，研究Ti、Ni在多层轧制复合过程中的组织演变、变形行为、变形协调性、界面形成及其作用机制，探讨高能态界面组织的扩散行为、扩散反应、金属间化合物的形成及发展规律，建立轧制复合和界面扩散模型，揭示制备工艺、组织、变形协调性、界面结构、相组成等与性能之间的关联性，为Ti/Ni多层形状记忆复合材料的制备、性能调控及应用提供理论依据和技术支持。

层状复合材料因其优异的力学、物理和化学性能在各个领域中得到了广泛的应用。然而，因其组元材料性能差异，在塑形变形过程中，复合材料结构控制、变形协调性和界面调控等问题导致材料性能受到限制。. 本项目以纯钛和纯镍为原材料，通过热模拟，研究Ti/Ni层状复合材料变形行为，构建本构方程；建立功率耗散图和热加工图，确定复合材料最佳加工区；分析变形过程中的组织演变。通过累积叠轧，制备出Ti/Ni多层结构复合材料，研究了热处理工艺对界面结构演变、扩散反应、相组成及其演变的影响。主要研究结论如下：.Ti/Ni多层复合材料流变应力随变形温度的降低或应变速率的升高而增加。在500-700℃/0.001-1.0/s下，Ni变形机制为加工硬化；在700 ℃/0.001/s，Ti变形机制为动态回复，在500-600 ℃/0.001 /s和700 ℃/0.1-10.0/s，变形机制为加工硬化；在700 ℃/0.001 /s条件下，层状结构变形较为均匀。建立的Arrhenius本构方程可较好地预测Ti/Ni多层结构复合材料的变形行为，其R值为0.965，AARE值为9.207%。在应变为1.0时，最佳热加工参数为630-700 ℃/0.001-0.003/s，峰值功率耗散系数为0.40。. Ti/Ni/Ti复合材料应变越大，材料结构比例参数随变形温度和应变速率变化较大。建立的SR-SCA本构方程可以较好地预测Ti/Ni/Ti复合材料的变形行为，其R值为0.9803，AARE值为7.92%。在应变为1.0时，最佳热加工参数为680-740 ℃/0.004-0.018/s，峰值功率耗散系数为0.445。典型的失稳形式为：结构不均匀、界面结合不良。. Ti/Ni经累积叠轧及热处理后，Ti/Ni界面出现TiNi3、Ti2Ni、TiNi三种化合物共存。随热处理温度升高，纯Ni先反应消耗完，多余的Ti与新生成的TiNi3反应生成TiNi和Ti2Ni，界面结构最终组织为TiNi和Ti2Ni两相混合组织。