CuAlNi单晶压缩时相变带的生长和传播

Formation and Growth of Martensite Bands in CuAlNi Single Crystal under Compression

利用高分辨率的CCD系统监测到CuAlNi单晶表现出相变伪弹性时的压缩变形过程.在压缩过程中观察到相变时马氏体的生长和传播,发现了在相变过程中出现交叉的相变带.利用红外相机拍摄了CuAlNi单晶相变过程中的温度变化规律.结果表明,在加载到单晶相变的过程中,已发生相变的区域温度逐渐升高;退载时,随着相变的结束,相变区域温度逐渐下降.压缩实验表明,加载时,母相中马氏体生长所需的应力比接下来继续相变时所需的应力要大;退载时,马氏体区域内奥氏体生长应力要比继续相变时所需的应力低.实验表明,利用红外成像技术可以研究记忆合金的相变规律.

The deformation process of a CuAlNi single crystal shape memory alloy (SMA) was monitored with high sensitive CCD system and it shows pseudoelasticity under compression. The formation and growth of martensite bands were observed during the compressing process. The martensite cross-band was found in the surface of specimen when the CuAlNi single crystal SMA is compressed. The infrared camera was used to keep record of the temperature change of sample surface in the process of transformation. The results demonstrate that the temperature in the transformed martensite region goes up gradually during loading, while that goes down during unloading with the transformation process coming to an end. It is also shown that during loading, the stress required for the formation stage of martensite is higher than that for the growth stage of martensite while during unloading. By contrast, the stress required for austenite formation in a martensitic region during unloading is lower than that of austenite growth. The martensitic transformation process of CuAlNi single crystal SMA can be studied with infrared thermal imaging technology.