Deposition morphology and intermetallic compound formation at the bonding interface in alloyed steel on an aluminum alloys using laser directed energy deposition

When depositing dissimilar materials, several principal factors must be considered, including differences in melting points, the behavior of molten metals, and the formation of intermetallic compounds at interfaces. If the depositing conditions are not appropriate, laminating is not stable and interfacial delamination may occur. Therefore, the quality of the first layer of laminate is especially important to achieve a good adhesion. This study investigates the phenomena occurring near the interface during laser directed energy deposition. The results show that laser scanning speed significantly changes the deposition morphology. As the scanning speed increases, the deposition width decreases, while the melting width and depth increase. Under high scanning speed conditions, droplet sizes become smaller. So, the molten metal temperature rises rapidly during heating. The substrate is also heated more effectively. At the bonding interface, the dissolution of the aluminum alloy substrate and the formation of Fe-Al intermetallic compounds are occurring. These intermetallic compounds consist of elements from both the substrate and the deposition material. Furthermore, the growth rate of the intermetallic compounds at the bonding interface of silicon-containing aluminum alloys decreases as a result of the reduced diffusion rate.