## 2 Experimental Procedure  
CM247 LC powder was procured from Carpenter Additive Co., with particle sizes ranging from 15 \(\upmu\)m to 45 \(\upmu\)m. The chemical composition of CM247 LC is identical to that of casting CM247 LC by measuring powders via X-ray fluorescence (XRF, S8 Tiger, Bruker, Karlsruhe, Germany) [25]. We used an EOS M290 (EOS, Krailling, Germany) laser powder bed fusion (L-PBF) machine for SLM. The scan speed, laser power, and layer thickness were used as parameters to characterize the thermal conductivity, as shown in Figure 1. SLM was carried out using an Yb fiber laser. To prevent oxidation, a low oxygen level was maintained in the working environment using argon gas with flow rate of 20 m\({}^{3}\)/h. The SLM machine controls the laser power, scan speed, layer thickness, and hatch spacing to fabricate samples. The laser power represents the intensity of the Yb fiber laser, the scan speed is the rate at which the powder is melted using a laser in one layer, the layer thickness denotes the layer of the powder to be melted, and the hatch spacing is the distance between layers. Samples were prepared using laser powers of 100 W, 150 W, and 200 W; scan speeds of 1200 mm/s and 1800 mm/s; and layer thicknesses of 20 \(\upmu\)m, 25 \(\upmu\)m, and 30 \(\upmu\)m. A scanning rotation angle of 67\({}^{\circ}\) was used to minimize defects caused by thermal residual stress [26]. The cross-plane direction is parallel to the building direction, and the in-plane direction is perpendicular to the stacking direction. We compared the differences in anisotropic thermal conductivity by measuring the microstructure, thermal conductivity, and electrical conductivity in the cross-plane and in-plane directions.  
X-ray diffraction (XRD) spectra were obtained using high-resolution XRD (SmartLab, Rigaku, Tokyo, Japan) with CuK\(\alpha\) radiation. Measurements were performed in the 20 range of 20-80\({}^{\circ}\) with a step size of 0.02\({}^{\circ}\) at room temperature.  
Three density measurement methods are commonly used in SLM: Archimedes' method, microstructure analysis, and X-ray scanning [27]. Archimedes' method is fast and easy to use. It is also accurate and repeatable at low density. Microstructure analysis involves determining the relative density by analyzing pores based on a scanning electron microscope (SEM, IT-500 HR, JEOL, Tokyo, Japan) or optical microscope (OM, Olympus, Tokyo, Japan). SEM or OM analysis programs calculate partial areas, and therefore not all cross-sections are represented. Because the program measures a random part, the relative density varies depending on the magnification at low density. X-ray scanning can derive the density by analyzing the distribution of pores inside a material in three dimensions. The density may vary depending on the X-ray scan resolution. In this study, we used [PERSON] method, which allows reliable results to be obtained repeatedly regardless of density. In addition, to  
Figure 1: Schematic of parameters for SLM and property measurement direction.  
observe the morphology and grain size, the samples were etched in 2% nitric acid for a few minutes. An OM was used to characterize the microstructure.  
To characterize the anisotropy in thermal conductivity according to the building direction of the sample, the samples were prepared in the cross-plane and in-plane directions. The cross-plane direction is parallel to the building direction, and the in-plane direction is perpendicular to the building direction. The temperature-dependent thermal diffusivity was measured using a laser flash apparatus (LFA 457 MicroFlash, NETZSCH, Selb, Germany) under a nitrogen environment from 100 \({}^{\circ}\)C to 1100 \({}^{\circ}\)C at 100 \({}^{\circ}\)C intervals. In addition, the electrical conductivities were measured using an electrical resistance measurement system (ZEM-3, ULVAC-RIKO, Yokohama, Japan) to decompose the total thermal conductivity into electronic and lattice thermal conductivities.