Shape memory effect at low temperatures in Cu-Al-Mn alloys

Shape memory alloys have the ability to generate large recovery stresses and strains due to shape memory effect, resulting in higher energy density than other actuator materials. Ti-Ni alloys show good shape memory effect, but the martensitic transformation is hard to occur at temperatures below 150 K due to increasing hysteresis. On the other hand, Cu-Al-Mn (CAM) has been reported to exhibit superelasticity with small hysteresis even at 4.2 K, and is expected to be actuated at cryogenic temperatures. In this study, martensitic transformation temperatures and shape memory effect under tensile stress were investigated in CAM alloys with different Mn contents.

The martensitic transformation temperatures decreased with increasing Mn content. The strains during cooling and heating under different constant tensile stresses were measured. The results show that CAM alloys exhibit shape memory effect over a wide temperature range from low temperatures with high work outputs comparable with other shape memory alloys.