Co-processing metals with distinct compatibility levels through multi-material laser powder bed fusion

Additive manufacturing (AM) combines geometric flexibility with minimal material waste due to its near-net shape capabilities. Among AM techniques, laser powder bed fusion (LPBF) stands out for its fine resolution and ability to process a wide range of metals and alloys with near-full density. One of the key innovations driving the evolution of AM is the development of multi-material processes, particularly multi-material LPBF (MMLPBF), which expands design possibilities, enables the fabrication of functional parts without additional assembly, and offers more efficient use of cost- and energy-intensive feedstock. Despite its potential, MMLPBF of geometrically complex 3D parts poses significant challenges due to its dependence on precise deposition methods and the intricate physical interactions that arise between different materials. These material-dependent interactions can modify the processing window and increase the likelihood of defects when compared to conventional single-material printing. As such, this study investigates the MMLPBF processing of bimetallic combinations that exhibit varying degrees of dissimilarity in terms of miscibility, thermal and physical properties. Microscopy and diffraction techniques are employed to evaluate how processing strategies influence part quality across distinct material systems —from closely related alloys like 17-4 PH and 316L stainless steels to more dissimilar combinations such as aluminum alloy and steel. In such a dissimilar pair, poor miscibility and contrasting thermophysical properties promote the formation of brittle intermetallic compounds and residual stresses at the interface, making the reliable fabrication of a sound bond a complex task.