Microstructures and wear properties of directed energy deposited materials on substrates containing FCCZ structures

In this study, we investigated the effect of the internal lattice structure of a substrate on the heat transfer properties and deposited material during the directed energy deposition (DED) process. A substrate containing a face-centered cubic with Z-axis (FCCZ) structure was fabricated by powder bed fusion (PBF). We fabricated single-layered and double-layered lattice substrates according to the number of layers of the lattice structure, and employed DED to deposit heterogeneous materials on the substrate. Experimental results showed that the lattice substrate exhibited excellent thermal and cooling properties owing to its small volume and large surface area. In particular, the high heating rate of the double-layered lattice substrate increased the temperature near the melting pool on the substrate, thereby increasing the width and depth of the deposited beads. Conversely, fast cooling of the lattice substrate led to the formation of a dense microstructure with uniform cellular grains in the deposited material. Furthermore, it suppressed the formation of laves phases, resulting in an increase in the hardness of the deposited part on the lattice substrate compared to that of the solid substrate. The high surface hardness of the deposited part on the lattice substrate minimized the deformation of wear tracks and reduced wear loss. Therefore, the results obtained in this study reveal that the quality and mechanical properties of materials deposited by DED can be controlled through the structure of the substrate.