Wire-and powder-based direct energy deposition of NiTi-CuSn10-SS316L

Additive manufacturing (AM) is a rapidly advancing method with the ability to produce complex geometries layer by layer. AM shows great promise for joining dissimilar metals. However, direct energy deposition (DED) of nitinol (NiTi) and 316 stainless steel (SS316L) encounters significant difficulties due to the development of brittle Fe-Ti intermetallic compounds. A copper alloy (CuSn10) interlayer was introduced to prevent their formation. This study utilizes a wire- and powder-based DED approach, eliminating the need for feedstock switching. Fine CuSn10 powder was specifically applied for the interlayer, resulting in distinct bonding mechanisms at the interfaces. Interdiffusion resulted in fishbone microstructures at the CuSn10-SS316L interface, whereas the NiTi-CuSn10 interface exhibited dendritic structures with evenly distributed elements. Microhardness analysis revealed a sharp variation across the layers …