基于精确塑性成形成性的异种形状记忆合金复合管微观结构演变机理及界面结合机制

In the present study,a new conception of composite pipe of dissimilar shape memory alloys is put forward, and thus accurate plastic forming for perfect properties based on isothermal extrusion as well as ball spinning is used to bond composite pipe of dissimilar shape memory alloys, which develops a new approach to manufacturing the composite pipe of dissimilar shape memory alloys and widens a new field of engineering application of the composite pipe of dissimilar shape memory alloys.According to the original pipe blanks of typical Fe-based, Cu-based and NiTi-based shape memory alloys,by combining finite element simulation and cellular automaton simulation,from the macroscale, mesoscale, microscale and atomic scale perspective,it shall be able to lay the scientific and theoretical foundations for realizing industrilization of the composite pipe of dissimilar shape memory alloys based on plastic deformation as well as widening the engineering application field of the composite pipe of dissimilar shape memory alloys to investigate deformation mechanism and mechanical behavior of the composite pipe of dissimilar shape memory alloys under plastic deformation,analyze the basic evolution of microstructures of the composite pipe of dissimilar shape memory alloys under plastic deformation,reveal the basic mechanism of interface bonding of the composite pipe of dissimilar shape memory alloys under plastic deformation,explore the basic mechanism of shape memory effect of the composite pipe of dissimilar shape memory alloys,obtain the property evaluation standard of the composite pipe of dissimilar shape memory alloys and establish the model of the optimum process parameters of plastic deformation which contributes to manufacturing the composite pipe of dissimilar shape memory alloys with high quality.

本项目提出了异种形状记忆合金复合管的新概念，并采用等温挤压和滚珠旋压精确塑性成形成性实现异种形状记忆合金复合管的连接加工，开辟了形状记忆合金复合管材制造与应用的新途径。通过选择典型的铁基形状记忆合金、铜基形状记忆合金和镍钛基形状记忆合金为原始管坯，结合有限元数值模拟技术和元胞自动机组织模拟技术，从宏观尺度、介观尺度、微观尺度和原子尺度出发，研究异种形状记忆合金复合管塑性变形机理及力学行为，分析异种形状记忆合金复合管塑性变形微观结构演变的基本规律，揭示异种形状记忆合金复合管塑性变形界面结合的基本机制，探索异种形状记忆合金复合管形状记忆效应的基本机理，获得塑性变形连接的异种形状记忆合金复合管的形状记忆效应等性能评价指标，建立获得高质量异种形状记忆合金复合管的塑性成形工艺参数优化模型，为实现异种形状记忆合金复合管塑性成形的产业化、拓宽异种形状记忆合金复合管的工程应用领域提供科学的理论基础。

本项目提出了异种形状记忆合金复合管的新概念，即成形出内层为镍钛基形状记忆合金管、外层为铜基或铁基形状记忆合金管的复合管。该异种形状记忆合金复合管综合了内外管各自的优点，弥补了各自的不足，内层管保持了良好的形状记忆效应和耐蚀性，外层管则保持了良好的加工性能和低成本，这对于拓宽形状记忆合金管接头的工程应用领域具有重要的意义。因此，选择合适的制造技术，获得高质量的异种形状记忆合金复合管，是保证其走向工程应用的关键。本项目以铁基、铜基和镍钛基形状记忆合金为载体，以等温精密挤压工艺实验、滚珠旋压工艺实验、金属微观组织表征实验、金属力学性能实验、热处理实验为手段，结合宏观有限元、晶体塑性有限元和分子动力学等模拟方法，揭示了形状记忆合金塑性变形机理及微观结构演变规律，为异种形状记忆合金管接头的精确塑性成形提供了科学的理论基础。自行构建了铁锰硅铬镍、铜铝镍、镍钛铁、镍钛铜和镍钛铌形状记忆合金的高温本构方程，为异种形状记忆合金复合管等温精密塑性成形宏观有限元模拟提供了材料模型。研究发现，异种形状记忆合金复合管塑性变形过程中内外管界面的协调性对界面的结合具有重要的影响，建立异种形状记忆合金复合管等温精密挤压成形和滚珠旋压成形的界面协调准则具有重要的意义。异种形状形状记忆合金复合管界面的大塑性变形纳米晶化和非晶化有利于界面的结合，并显著降低成形温度。构建了二元镍钛形状记忆合金和三元镍钛铁形状记忆合金的晶体塑性本构模型，采用晶体塑性有限元法研究了滑移系对其塑性变形的贡献，揭示了其显微组织、变形织构和位错密度的演化规律。采用分子动力学模拟，揭示了镍钛形状记忆合金应力诱发马氏体相变、相变孪生以及去孪生的物理机制。