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.

In recent years, demand for lightweight materials with excellent thermal conductivity, rigidity, and corrosion resistance has been increasing, especially in electric vehicles and digital devices. Magnesium alloys, which are light-weight, have high specific strength, and excellent thermal conductivity, are attracting attention. among Mg-Al alloys, Mg-Al-Ca (AX) alloys have improved thermal conductivity but reduced corrosion resistance. adding misch metal and manganese to AX64 has shown the possibility to improve both properties. The possibility of improving both properties has been demonstrated. In this study, we focused on the AXEM6400 alloy (Mg-6%Al-4%Ca-0.4%Mm-0.2%Mn) and investigated the effect of molten metal temperature on its properties. The results show that corrosion resistance due to Al 8Mn 4Ce precipitates increases and the internal defect volume decreases at the semi-solidification temperature. In addition, the refinement of the cell structure at this temperature improves tensile strength and hardness. The optimum processing temperature balances performance and manufacturability.

Transition of oxide layers on Al-1Mg alloys during heat treatment at 550°C were analyzed with Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscope (TEM). A uniform film of aluminum oxide (Al-O) was observed on the surface of the specimen without heat treatment and its thickness was about 4.5 nm. During heat treatment, magnesium oxide (MgO) formed first locally, followed by complex oxide of aluminum and magnesium (Al-Mg-O) formed around the MgO to replace the Al-O film. The size of the MgO was about 30 nm and they grew first to inside and to outside afterwards. A ring pattern was observed from the electron diffraction at MgO, indicating the local MgO was polycrystalline.