Property tailoring in multi-material Laser Directed Energy Deposition of High-Speed SynRel rotors

High-speed electric motors operating up to 100 krpm are required in subsystems such as fuel cell air compressors, where rotor architectures must balance electromagnetic efficiency and mechanical robustness. This study investigates how Laser Directed Energy Deposition (L-DED) allows property tailoring in FeSi2.9/316L bimetallic rotors by treating layer architecture as a controllable design variable. The introduction of interlayer machining further expands the design space by enabling thinner paramagnetic regions, while modifying the thermo-mechanical cycles and interfacial microstructure. Through combined mechanical testing, microhardness mapping and electromagnetic performance simulation and measurement, the relationship between process, design and properties is analyzed. Results show that thinner 316L layers increase inductance and reduce torque ripple, whereas thicker layers improve tensile performance and simplify processing. These findings demonstrate that laser-based multi-material deposition can strategically balance electromagnetic efficiency and mechanical behavior in bimetallic rotors.