Tension–Compression Asymmetry of Superelasticity in Unidirectionally Solidified Cu-Al-Mn Shape Memory Alloy

摘要

The unidirectionally solidified Cu-Al-Mn shape memory alloy with strong <001>-oriented texture along the solidification direction and high length-diameter ratio columnar-grained structure exhibits excellent superelastic properties compared to the Ni-Ti alloys. In this paper, the tension–compression asymmetry of unidirectionally solidified Cu71Al18Mn11 alloy was researched by the geometrically nonlinear theory and superelastic experiments. The results show that the tension–compression asymmetry of the alloy has a significant anisotropy. The theoretical asymmetry ratio of transformation strain along <011> reaches 14.2%, which is larger than other orientations. The tension and compression superelastic experiment research of unidirectionally solidified Cu71Al18Mn11 SMA along the direction parallel (<001> grain orientation) or perpendicular (<001>-<011> grain orientation) to the solidification direction indicates that their superelastic strain, transformation strain, elastic modulus, transformation platform slope, and critical stress have obvious tension–compression asymmetry.