Cyclic Properties of Superelasticity in Cu–Al–Mn Single-Crystalline Sheets with Bainite Precipitates

Microstructure, Vickers hardness and cyclic superelastic properties at room temperature were examined for Cu-Al-Mn single-crystalline sheets aged at 200 °C for various time periods. The bainite plates started to appear from about 9 ks and the density drastically increased from 18 to 30 ks and the Vickers hardness was strongly affected by the density of the bainite plates. In the sample with a little amount of bainite plates, the superelastic properties were basically similar to those in the bainite-free sample. In the samples with a high density of bainite, however, the transformation critical and hysteresis stresses and the dissipated energy were high and large for the initial stage of cycles, respectively. They drastically and monotonically decreased with increasing cycle number and the residual strain increased from the initial stage, unlike those in the bainite-free sample.