形状记忆合金微观力学行为的实验研究

The microscopic full field deformation of shape memory alloy(SMA) is characterized by combining digital image correlation and scanning electron microscope (SEM) moire method. The fabrication techniques of micro-scale speckle patterns and high frequency gratings are developed and the optimized processing parameters will provide good guidence for the fabrication of high quality speckle patterns and gratings. A compact loading system is designed and manufactured to realize the characterization of basic mechanical properties of SMA under microscope, including the tensile test, compression test and three point bending test. Random phase shifting technique is introduced into SEM moire method to realize the automatic high precision preocessing of moire fringes. The influences of martensite and crystalline on the microscopic deformation of SMA are analyzed. The effect of annealing and aging treatments on the microscopic deforamtion and martensite is illustrated.The evolution law around the crack tip of SMA is studied and the stress intensity factor is calculated. The results will provide reliable experimental data for the foundation of theory model and the reliability design of SMA and the developed techniques will provide effective tools to quantitatively characterize the microscopic full field deformation of SMA.

本项目拟通过数字图像相关和扫描电镜云纹法相结合的方法来研究形状记忆合金材料的微观全场变形。发展制备微米散斑和高频光栅的工艺，优化其工艺参数，为制得高质量的散斑和光栅提供技术工艺指导。发展光学显微镜下的数字图像相关测量技术，研制开发与成像设备相匹配的紧凑型加载设备，以实现试件的拉、压、三点弯等基本的力学性能检测。发展扫描云纹的随机相移技术，以实现云纹条纹的高精度、自动化处理。分析形状记忆合金材料微观变形和马氏体相变之间及微观变形和晶粒参数之间的关系，揭示退火、时效处理等对其微观变形和马氏体相变的影响机制，研究形状记忆合金微裂纹尖端的变形演化规律和应力强度因子表征。本项目的研究成果将为形状记忆合金理论模型的建立和可靠性设计提供可靠的实验数据，为形状记忆合金微观全场变形的定量测量与表征提供有效的实验手段。

本项目通过数字图像相关和扫描电镜云纹法相结合的方法研究了钛镍形状记忆合金材料的微观力学行为。发展了离心甩胶制备微米散斑和FIB制作高频光栅的工艺，优化了其工艺参数，为制得高质量的微尺度散斑和光栅提供技术参考。研制开发了与超景深显微镜相匹配的紧凑型加载设备，可对试件进行拉、压、三点弯等形式的加载，与超景深显微镜下的数字图像相关技术相结合，可实现试件表面微观变形的测量。发展了扫描云纹的随机相移技术，编制了随机相移云纹图的处理程序，可实现云纹条纹的高精度、自动化处理。实现了TiNi形状记忆合金微观变形的定量测量和分析，揭示了固溶处理、时效处理等对其力学行为和马氏体相变的影响机制，分析了晶界对微观变形的影响，研究了形状记忆合金微裂纹尖端的变形演化规律和I型裂纹的应力强度因子表征方法。本项目的研究成果为形状记忆合金微观全场变形的定量测量与表征提供了有效的实验手段。