## 1 Introduction
[PERSON] et al. [22] analyzed the microstructure evolution of the Fe-18.9 Mn and Fe-18.5 Mn-Al-C alloys solidified during the SLM process and presented 2D results. [PERSON] et al. [23] applied a 3D FEM model for a thermal task and a 2D cellular automata (CA) for simulation of microstructure evolution with dendritic grain growth. [PERSON] et al. [24] investigated the complex solidification process during laser welding of the 5083 aluminum alloy. The model combines a macroscale model for heat and mass transfer, a microscale model for polycrystalline alloy solidification, and the continuous Gaussian nucleation distribution model for heterogeneous nucleation. [PERSON] and [PERSON] [25] studied vaporization and its influence during powder bed fusion processes. [PERSON] et al. [26] simulated the SLM powder-layering process, powder movement, and packing on the particle scale. On the basis of the discrete element method (DEM), their study investigated the flowing behavior of powder layered by a blade, and the model was validated by the results of the experiment. [PERSON] et al. [27] performed experimental studies of the thermal and fluid behavior of the powder layer during SLM and then applied computational research to the SLM process, where DEM and CFD were used to simulate the spread of the powder layer and the fusion of the powder layer, respectively. [PERSON] et al. [28] used DEM to simulate the random distribution of particles of spherical shapes of different sizes and the 3D finite difference method (FDM) for thermal simulations. [PERSON] et al. [29] presented a multiphase and multiphysics model developed for the selective laser melting process, where fluid flow, solidification, and heat transfer were included. The DEM and volume-of-fluid (VOF) methods were applied to generate the powder bed and capture the free surface of the melts, respectively. Physical behaviors such as surface tension, the Marangoni effect, vapor recoil, and radiation were considered. The remolten region between two neighboring tracks in the horizontal and vertical directions was predicted, and the effects of the scanning spacing and laser power on the width and depth of the remolten region were investigated. [PERSON] et al. [30] proposed a ray-tracing heat source model for a mesoscale computational fluid dynamic (CFD) simulation of the SLM process. Multiple reflections of the laser beam at the surface of the metal powders were taken into account in the modeling. It was integrated into the commercial software, FLOW3D. A single laser path was simulated. [PERSON] et al. [31] used DEM and the finite volume method (FVM) to build a 3D numerical model to simulate the SLM process of SS316L stainless steel. The single track was verified. A CFD model was set up and implemented in the FLOW-3D CFD software. [PERSON] et al. [32] simulated a similar laser melting deposition process with a single track using a mesoscopic CFD model for AISI 304 stainless steel with experimental verification. Spherical particles were deposited in one layer. Recently, multi-material AM processes have also been modeled. [PERSON] and [PERSON] [33], using the coupled level-set and volume-of-fluid method for multiphase thermal fluid flow simulation of very complicated AM processes, simulated and analyzed the fluid flow dynamics and mass loss characteristics due to metal vaporization. They obtained, among others, results connected with the formation of the melt pool, keyhole, and flow for different elements, as well as the mass loss rate resulting from vaporization. A multi-material model for the lattice Boltzmann-based simulation of the mixing of two elements to a binary alloy via PBF is presented by [PERSON] et al. [34]. The thermodynamic model comprised mass, momentum, and enthalpy conservation equations, including element-specific mass conservation and the effect of enthalpy diffusion. The material model considered concentration-dependent material parameters such as heat capacities and latent heat.