普通多晶组织Cu基形状记忆合金由于变形协调能力差，易发生晶间断裂而导致记忆性能和疲劳性能差，限制了合金的广泛应用。申请人从组织设计角度出发，采用定向凝固方法制备了具有轴向强<001>织构和平直低能晶界特征的柱状晶Cu-Al-Mn形状记忆合金，合金的超弹性应变可达到10%以上，达到单晶合金水平。基于柱状晶Cu-Al-Mn合金在高应变（> 4%）下反复应用的需要，分析和研究合金的疲劳力学行为及其相关机制具有重要意义。本项目将围绕着柱状晶Cu-Al-Mn形状记忆合金在超弹性循环过程中的疲劳性能演变机制、疲劳力学行为、疲劳性能提升机制等基础科学问题，通过采用宏观-介观-微观多尺度分析方法，深入研究合金在高应变下的超弹性疲劳中形变-相变行为和相关机理，阐明柱状晶组织合金的超弹性疲劳力学行为及疲劳性能提升的本质。并由此建立起相应的疲劳力学模型，为进一步提高合金的应用前景和开发设计应用器件提供理论参考。

Ordinary polycrystalline Cu-based shape memory alloys are limited in widely used due to their low shape memory properties, poor fatigue property, and susceptible to intergranular cracking. Based on the perspective of microstructure design, columnar-grained Cu-Al-Mn shape memory alloy, with the characteristics of strong <001>-oriented texture and straight low-energy grain boundary, is prepared by unidirectional solidification. The superelastic strain of the columnar-grained Cu-Al-Mn alloy can reach above 10%, which is comparable with the single crystal counterpart. Because the columnar-grained Cu-Al-Mn alloy has to be repeatedly used under high strain (> 4%), it is of great significance on analyzing and researching its fatigue mechanical behavior and corresponding mechanism. This project focuses on the basic scientific problems of superelastic fatigue property evolution mechanism, fatigue mechanical behavior under cyclic loading, and the fatigue property improvement mechanism of the columnar-grained Cu-Al-Mn shape memory alloy. Through multi-scale (macroscopic mesoscopic & microscopic) analysis methods, this project in-depth researches the phase transformation and deformation of the columnar-grained Cu-Al-Mn alloy in the process of superelastic fatigue, and clarify the nature of columnar-grained structure significantly increased the material fatigue property. Thus, this project will establish the corresponding fatigue mechanical model, and then provide theory reference for further improving application prospect and designing application devices.