Bending-Induced Triple Twins in Single-Crystalline Ni-Mn-Ga Samples: Measurements with Digital-Image-Correlation (DIC) Method

Three-point bending tests are conducted on two single-crystalline Ni-Mn-Ga samples. The responses of the samples are recorded and the strain distributions in the samples are measured by using the digital-image-correlation (DIC) method. It is observed that two connected triple twins are generated in the middle portion of each sample. Correspondingly, the response curves exhibit some peak-valley combination segments. The characteristics of mechanical behaviors of the samples are discussed and are compared with those observed in the axial compression tests. The arrangements of lattice structures in the different variant regions are also analyzed.