Copper lattice-embedded steel composite: One-step fabrication and its thermal and mechanical properties

Abstract

3-dimensional (3D) lattice structures can expand ranges of material properties. Not only material's microstructure, but their geometry strongly varies the properties, offering design freedom for multifunctional materials. In the same context, incorporating 3D lattice structure within composites may realize surpassing material properties. However, due to manufacturing challenges, lattice-patterned metallic composites have been largely unexplored. Here, as a model study, we report the first fabrication of lattice-patterned copper-316L stainless steel composites and experimental investigation of their thermal and mechanical properties. Steel-copper composites with a simple cubic-patterned copper structure are fabricated through direct energy deposition and densified via post-processing. Transmission electron microscopy analysis confirms that steel constituent elements are present within the copper lattice, and underwent diffusion and subsequent phase separation. Using effective thermal conductivity analysis, the effects of the fabrication process on the heat transfer efficiency of the composites and the thermal contact conductance at the steel-copper interface are evaluated. Furthermore, the compressive strength of the composites, enhanced by the incorporation of the steel matrix, was assessed through compression testing. The present work demonstrates that lattice-patterned composites for industrial applications requiring high thermal conductivity can be fabricated using direct energy deposition and provides optimization guidelines for their properties.