Copper-based shape memory alloys (SMAs) are cost-effective alternatives to NiTi, with CuAlMn alloys standing out for their high ductility, good cold workability, and easy processing. These alloys can be produced in open-air furnaces, and the rapid investment casting (RIC) technique allows the fabrication of near-net-shape components from polymer or resin printed models. This work evaluates the effect of RIC reprocessing on a CuAlMn superelastic SMA, comparing it with the original ingot and applying the process to fabricate an S-shaped metamaterial designed to exhibit superelasticity at room temperature. An S-shaped metamaterial is an architected structure based on periodic S-shaped unit cells, enabling controlled deformation and tunable mechanical response for lightweight applications. The alloy was characterized by SEM-EDS, XRD, optical microscopy, and DSC, while mechanical behavior was assessed through ultramicrohardness, tensile, and compression tests, complemented by finite element simulations. The results showed that RIC reprocessing preserved the alloy’s chemical homogeneity and superelastic properties, with only slight grain growth (~15%) and minor compositional variations. The reprocessed specimen exhibited good mechanical recovery, with 1.41% residual strain at 7% deformation. The S-shaped metamaterial showed stable superelastic behavior under cyclic loading, increasing stiffness with temperature and maintaining constant energy dissipation. The experimental results corroborated the finite element simulations, which were employed as a tool to better understand the stress-induced martensitic transformation concentrated in the S-shaped cells. Overall, the study demonstrates that RIC reprocessing preserves the superelastic functionality of CuAlMn alloys, enabling the fabrication of S-shaped architected structures that exhibit thermomechanically stable behavior and controlled mechanical response under cyclic loading.
Alves et al. (Sun,) studied this question.