In this work, the influence of different heat treatments on the martensitic transformation and precipitation in polycrystalline Cu13%Al4%Ni shape memory alloys have been investigated. A CuAlNi strip were subjected to different heat treatments in order to obtain a variety of microstructures. In this way, the samples were aged at a temperature between 200 and 450 °C. Some specimens were heat-treated at 900 °C followed by ageing processes. The transformation temperatures were measured using Differential Scanning Calorimetry (DSC) method. To determine the mechanical properties, the samples were subjected to the tensile and hardness tests. Microstructural studies were performed using optical and scanning electron microscopies. According to the experimental results, increasing the ageing temperature up to 370 °C results in strength and transformation stress to increase. As the temperature rises to 350 °C, some precipitates appear in the microstructure. Once the temperature reaches 450 °C, there is no martensite in the microstructure. Accordingly, the hardness increases and the elongation decreases drastically in such a way that the alloy breaks in the elastic region. The solution treatment at 900 °C for 20 min yields the martensite to reappear in the microstructure resulting the hardness and strength to decrease and the elongation to increase. Ageing of the samples after solution treatment, increases the mechanical properties again but no precipitation takes place.

在这项工作中，研究了不同热处理对多晶 Cu13%Al4%Ni 形状记忆合金中马氏体转变和析出的影响。对 CuAlNi 带材进行不同的热处理以获得各种显微组织。通过这种方式，样品在 200 至 450 °C 的温度下老化。一些样品在 900 °C 下进行热处理，然后进行时效处理。使用差示扫描量热法(DSC)方法测量转变温度。为了确定机械性能，对样品进行拉伸和硬度测试。使用光学和扫描电子显微镜进行显微结构研究。根据实验结果，将时效温度提高到 370 °C 会导致强度和转变应力增加。随着温度升高到 350°C，显微组织中会出现一些析出物。一旦温度达到 450 °C，显微组织中就没有马氏体了。因此，硬度增加，伸长率急剧下降，合金在弹性区域断裂。在 900 °C 下进行 20 分钟的固溶处理使马氏体重新出现在显微组织中，导致硬度和强度降低，而伸长率增加。固溶处理后样品的老化，再次提高了机械性能，但没有发生沉淀。显微组织中没有马氏体。因此，硬度增加，伸长率急剧下降，合金在弹性区域断裂。在 900 °C 下进行 20 分钟的固溶处理使马氏体重新出现在显微组织中，导致硬度和强度降低，而伸长率增加。固溶处理后样品的老化，再次提高了机械性能，但没有发生沉淀。显微组织中没有马氏体。因此，硬度增加，伸长率急剧下降，合金在弹性区域断裂。在 900 °C 下进行 20 分钟的固溶处理使马氏体重新出现在显微组织中，导致硬度和强度降低，而伸长率增加。固溶处理后样品的老化再次提高了机械性能，但没有发生沉淀。