## 2 Materials and Methods  
For the experimental procedure, a gas atomized Inconel 718 powder (Praxair NI-202-3) with a particle size of d90 = 45 \(\upmu\)m and d10 = 16 \(\upmu\)m was used. The coating was applied to a round blank of grade AISI 316L with a thickness of 6 mm and a diameter of 100 mm. Prior to the coating process, the blanks were cleaned with alcohol. The coating was performed with a high-speed laser cladding system, consisting of a TRUMPF BEO D70 Optic, which was equipped with the prototype of a TRUMPF 7-ray nozzle, and a TRUMPF TruDisk 6001 laser source. The powder was fed during the deposition process using a plate feeder. The feed rate, which results from the path velocity and the trace offset, was controlled by the axial rotation of a conventional industrial robot. The synchronization of both systems by the robot controller allowed for the implementation of a constant feed rate depending on the diameter during the entire coating process. The processing of the powder was carried out according to the parameters stated in Table 1.  
In order to remove the surface roughness, a grinding treatment and subsequent polishing were performed according to standard metallographic procedures. The thermochemical treatment by powder-pack boriding was carried out using a process routine developed for \begin{table}
\begin{tabular}{c c} \hline power (W) & 4000 \\ Spotsize (mm) & 1.8 \\ path velocity (m\(\cdot\)s\({}^{-1}\)) & 0.42 \\ trace offset (mm) & 0.3 \\ overlap (\%) & 83 \\ feeding rate (g\(\cdot\)min\({}^{-1}\)) & 35 \\ Ar gas flow rate (L\(\cdot\)min\({}^{-1}\)) & 12 \\ No. of passes & 1 \\ \hline \end{tabular}
\end{table} 
Table 1: Laser cladding parameters for Inconel 718.  
nickel alloys. In the present study, 50-100 nm B4C powders were chosen, since boronizing powder mixtures often allow for boronizing to be achieved in a shorter time for the same boronizing temperature compared to micron-sized powders [44]. The process parameters are shown in Table 2.  
The feedstock powder and the laser-clad coatings were subjected to X-ray fluorescence (XRF) analysis in a Fischerscope X-ray XAN device ([PERSON], Sindelfingen, Germany) to determine the chemical composition in three comparative measurements. An acceleration voltage of 30 kV, a current of 1 mA, a Ni primary filter, and a collimator diameter of 0.6 mm were applied. Metallographic cross-sections of the coating were prepared according to a metallographic standard routine. Etching was performed using a solution consisting of 50 mL HCl and 150 mL HNO3 with an etching time of 15 s. The microstructure of the coating was investigated by scanning electron microscopy (SEM) using an LEO 1455 VP (Zeiss, Oberkochen, Germany) microscope. The morphology, microstructure, and chemical composition were investigated by means of secondary and backscattered electron imaging. A surface microhardness measurement was carried out by nanoindentation. For this, a Fischerscope HM 2000 XYP (Helmut Fischer GmbH, Sindelfingen, Germany) with a Vickers tip was used for progressive measurement with a load of 10 mN. Borosilicate glass BK7 was used as the calibration standard. At least ten single measurements were considered for the calculation of the average microhardness and the standard deviation. Crystallographic studies were carried out by XRD measurements using a D8 DISCOVER diffractometer from the Bruker Corporation (Billerica, MA, USA). Monochromatic Co-K\(\alpha\) X-ray radiation was utilized for all measurements. A voltage of 40 kV, a current of 40 mA, a sampling rate of 24\({}^{\circ}\) h\({}^{-1}\), and a diffraction angle range of 20\({}^{\circ}\) to 130\({}^{\circ}\) was used. The X-ray sensor used was a LynxEye-XE detector, the aperture size after the beam gun was 2 mm, and a polycap was used to obtain a parallel beam emission. The data was evaluated using Rietveld refinement. Elemental analyses of the borided layers with depth resolution were performed by glow discharge spectroscopy (GDOS) with a GDA 750 (SpectrumaAnalytik GmbH, Hof, Germany).