Exploration of interface microstructures in additively manufactured multimaterial based on Ni, and Cu alloys through a cost-effective strategy

This study investigates microstructural transitions between Inconel-625 and CuNiSiCr alloys, processed via multimaterial L-PBF on a carbon steel substrate. The objective is to understand interface properties and optimize process parameters to improve material transitions. Single-material printing trials revealed greater processing challenges with CuNiSiCr primarily due to copper’s high reflectivity at the infrared laser wavelength, leading to lack-of-fusion defects. Conversely, Inconel-625 exhibited excellent processability, achieving a relative density of 99.37%. In multimaterial printing, applying intermediate Volumetric Energy Density parameters at the interface reduced defects and improved transition homogeneity. Microstructural analysis revealed a gradual variation in chemical composition, indicating significant elemental diffusion, along with grain-size heterogeneity, yet no evidence of interfacial cracking was observed. Although the primary focus of this work was the Inconel-625/CuNiSiCr interface, the adopted configuration also enabled a preliminary assessment of the interactions between the printed alloys and the steel substrate. These additional observations confirmed that distinct microstructural features arise depending on the deposited material, with CuNiSiCr showing a heterogeneous morphology and Inconel-625 forming a more continuous metallurgical bond. These findings highlight the potential of multimaterial L-PBF for advanced components, emphasizing the need for optimized transition region design to minimize defects and improve interface integrity.