Laser powder bed fusion of Cu/17-4 PH multi-material system: Microstructural evolution and structure-property relationships

The integration of copper alloys with high-strength steels through laser powder bed fusion (LPBF) offers a promising pathway toward multifunctional components combining superior thermal conductivity and mechanical performance. However, conventional bimetallic steel/Cu architectures fabricated by sequential deposition often suffer from interfacial defects arising from the large mismatch in thermophysical properties and the intrinsic immiscibility of the Cu-Fe system. In this work, a Cu/17-4PH multi material system was developed via mechanical powder mixing and processed by LPBF to promote a more homogeneous distribution of phases and mitigate sharp compositional gradients at the interface. Exploiting the rapid solidification conditions inherent to LPBF, the study investigates the extent of partial alloying, solute trapping, and microstructural refinement occurring within this pseudo-alloy. A comprehensive microstructural investigation, together with a deep mechanical characterization at the nanoscale, was performed to elucidate phase distribution, interfacial morphology, and diffusion-driven interactions between the Cu-rich matrix and the Fe-rich reinforcing phase. Nanoscale mechanical testing and thermal characterization, including evaluation of the thermal conductivity, were conducted to establish correlations between processing parameters, microstructure, and functional properties. The results demonstrated the potential of the powder mixing approach to engineer novel high thermal conductivity systems offering an improved trade-off between functional and mechanical performance for advanced thermal management and high-temperature applications.