Exploring thermomechanical functionality of CuAlMn as an extreme low temperature shape memory alloy

Solid state actuation characteristics of CuAlMn shape memory alloys (SMAs) are reported at extreme low temperatures (<-100 degrees C). The effects of composition on the martensitic transformation (MT) characteristics are demonstrated at low temperatures (below -200 degrees C). The thermomechanical experiments revealed that the alloys exhibited 2.9% actuation strain under 250 MPa at subzero temperatures. CuAlMn SMAs with different Mn concentrations displayed 2% superelasticity at temperatures lower than -100 degrees C. The results illustrate that CuAlMn SMAs are promising candidates for cryogenic actuation and superelastic applications. The results are significant because none of the well-known NiTi SMAs demonstrate reversible thermally-induced MT below -60 degrees C. These findings are important for enabling solid state actuation in space and subsea environments.