Process-aware spatial material design in laser powder bed fusion of multi-material structures: from material placement to service function
Laser powder bed fusion (LPBF) has opened a route to multi-material metallic components in which material composition, geometry and local function can be arranged within the same part. Most existing discussions emphasize whether dissimilar materials can be bonded successfully. This article shifts the focus from interface feasibility to process-aware spatial material design. The central question is not only how two materials can be joined, but how their locations, transition paths, local process windows and post-build reliability should be planned together. Multi-material LPBF is discussed as a design-to-manufacturing problem involving material-layout definition, thermal compatibility, powder delivery, local melt-pool control, data representation, simulation and service-oriented qualification. Particular attention is given to graded transitions, intralayer material placement, hybrid metal/polymer or metal/ceramic layouts, machine-learning-assisted parameter selection, powder cross-contamination and application-driven design in biomedical, energy, electronic and aerospace components. The review suggests that future work should move from isolated interface demonstrations toward validated design rules that link material distribution, local microstructure, defects and service performance.