## 2 Materials and Methods  
The powder alloying was manufactured by mechanical alloying using a planetary mill ([PERSON], Pulverisette 7, Germany), and the powder alloying process conditions were the same as in previous studies [7]. The amount of elemental powder used for alloying was calculated according to the molar ratio for producing FeCrCoNiAlTi\({}_{1.5}\)C\({}_{1.5}\). Figure 1a shows the experimental setup for the cladding process. The paste was prepared by addingdistilled water and polyvinyl alcohol and then dried in an oven by blading on AISI 304 stainless steel with a thickness of 1.5 mm, as shown in Figure 1b. The composition of the substrate and powder was analyzed with an inductively coupled plasma optical emission spectrometer (ICP-OES), and is represented in Table 1. The cladding process was carried out using a 6-axis robot ([PERSON], KR 100-3, Germany) and a multi-mode disk high power laser (Trumpf, HLD4002, Germany). A Yb:YAG solid-state laser with a wavelength of 1030 nm and a continuous wave was used. The laser beam was a circular beam with a diameter of 3 mm on the surface of the substrate. The cladding layer was manufactured in an area of 50 mm \(\times\) 60 mm, moving at pass intervals of 2.5 mm (Figure 1c) and was protected by argon gas. The laser output, which is the main variable, was selected by considering the change in the microstructure in the feasibility test. The cladding speed was constant at 10 mm/s, and the laser power was used in three conditions: 1.0 kW, 1.5 kW, and 2.0 kW. The samples were named EEMMC1.0, EEMMC1.5, and EEMMC2.0, which used entropy-enhanced metal matrix composites (EEMMC) and the laser power value. In multi-pass cladding, all passes except both end passes had overlapping areas on both sides, and the microstructure was analyzed in the non-overlapping zone. For each condition, 8 samples were taken and analyzed with an area of 12 mm \(\times\) 8 mm.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Name**} & \multicolumn{8}{c}{**Chemical Composition (wt\%)**} \\ \cline{2-9}  & **Fe** & **Cr** & **Ni** & **Al** & **Co** & **Ti** & **C** \\ \hline STS304 (substrate) & 72.2 & 18.2 & 8.0 & - & - & - & 0.06 \\ FeCrCoNiAlTi\({}_{1.5}\)C\({}_{1.5}\) (powder) & 16.3 & 14.9 & 17.2 & 7.9 & 17.2 & 21.0 & 5.3 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical compositions of substrate and powder.  
Figure 1: (**a**) schematic of the experimental setup. (**b**) HEAs powder dried on the substate before laser cladding. (**c**) Coating layer appearance after laser cladding.  
X-ray diffraction (XRD, Rigaku, MiniFlex, Japan) was employed for phase analysis. The microstructure of the samples was observed in back-scattered electron (BSE) mode using field-emission scanning electron microscopes (FE-SEM, Thermo Fisher, Quanta 200F, Switzerland). The particle area distributions of the reinforcing particles were analyzed using image processing software (Image-Pro Plus) using 8 FE-SEM images at 5000\(\times\) magnification. Element mapping was also measured using an electron probe microanalyzer (EPMA, Cameca, SX-100, France). Micro-Vickers hardness (Mitutoyo, HM-200, Japan) was measured by indenting 0.2 kg for 15 s. The hardness of the metal matrix and the reinforcing particle was analyzed separately with an ultra nano-indentation tester ([PERSON], UNHT3, Austria). The test conditions were paused for 10 s at the maximum load of 20 mN, and the loading and unloading rates were performed at 120 mN/min.