Arc-based additive manufacturing of Cu-Al-Mn shape memory alloys: microstructure, tensile behavior and superelastic properties

Cu-based shape memory alloys (SMA) are a class of materials with high potential industry adoption due to their intrinsic shape memory and superelastic properties. The application of this material has been studied for years in the as-cast and heat treated conditions. Additive Manufacturing (AM) of these alloys is only sparsely reported for laser powder bed fusion with no reports for the successful application of high deposition rate processes, such as arc-based ones, found in the literature. Thus, this work presents, for the first time, the successful fabrication of Cu-17Al-11.4Mn (at. %) SMA components via arc-based additive manufacturing using a gas metal arc welding system. The deposition process yielded a structurally defect-free wall with homogeneous microstructure. Optical and electron microscopy, and synchrotron X-ray diffraction confirmed the presence of columnar grains morphology due to the associated thermal cycling effects, and a primarily FCC phase. Tensile tests in both horizontal and vertical directions showed high strength and ductility with minimal anisotropy, while superelastic cyclic testing revealed stable hysteresis behavior up to 100 load-unload cycles, indicating high functional fatigue resistance. Further, a stress-induced transformation observed via in situ synchrotron X-ray diffraction during tensile loading underscores the material's suitability for superelastic applications. The present findings demonstrate the feasibility and advantages of employing arc-based additive manufacturing for processing Cu-based SMA, opening new pathways for cost-effective fabrication of functional components.