Additive manufacturing of Cu-Al-Ni shape memory alloys through laser powder bed fusion and laser metal deposition: Challenges and perspectives

Shape memory alloys (SMA) are functional materials exhibiting specific shape memory and superelastic effects, which are applied in many technological sectors, and in particular in the aerospace industries. On other side, additive manufacturing (AM) offers new processing capabilities of SMA and is already being applied to NiTi-based SMAs, but Cu-based SMAs are also attracting the attention because of some advantages over the NiTi SMA, particularly, they offer a broader transformation temperature range. In addition, AM open new expectations of producing components from different materials, directly in the space. However, AM of Cu-based SMAs constitute a challenge due to the inherent processing difficulties associated with its high thermal conductivity and the microstructure required to obtain good functional properties.

In the present work the same atomized powders of Cu-Al-Ni SMA were processed by two different additive manufacturing methods, laser powder bed fusion (LPBF) and laser metal deposition (LMD), and the processing parameters were optimized for each method. The microstructure and the mechanical properties of shape memory and superelasticity obtained in each case will be comparatively analyzed, being also compared with the ones obtained by the classical powder metallurgy route processed through hot isostatic pressing and hot rolling.

The SMA processed LPBF, exhibit a reproducible superelastic effect and shape memory above 2.5% strain. These results pave the road for further optimization with view to the applications of SMA produced by AM, and, eventually, producing specific actuators in the space.