## 3 Results and Discussion  
The macro- and microstructure investigations performed using the fibre laser allowed for comparing the surface layer as well as the shape and depth of the remelting area. The cross-sections of the layers achieved by the alloying process are shown in Figures 4 and 5. A general remark can be made that an increased laser power causes increases in the remelting depth and the surface roughness of the remelted area. The achieved microstructure is presented in Figure 6. Concerning the distribution phases that occurred in the Ag-Cr-Ni alloy, the microstructure was very well solidified without any defects or failures; some discontinuities were found, but for higher laser powers, the thickness was as high as approximately 143-380 \(\upmu\)m, depending on the power. The dendritic arms of the slowly solidified Ag matrix are relatively visible, revealing the heat transfer direction after the laser beam treatment at room temperature. \begin{table}
\begin{tabular}{c c} \hline
**Parameter** & **Value** \\ \hline Laser scanning rate, m/min & 0.5 \\ \hline Peak power, W & 2000-3000 \\ \hline Power feeding rate, g/min & 4.5 \\ \hline Argon flow rate through the nozzle & 8 \\ \hline Dimensions of the laser beam focus, mm & \(3\times 3\) \\ \hline \end{tabular}
\end{table} 
Table 2: Parameters of the fibre laser. Figure 4: Surface layer after Cr/Ni powder was fed into the Ag alloy; power: 2.0 kW; laser speed: 0.5 m/min. The EDS point analysis, presented in Figure 8 and Table 3, reveals the chemical composition of the alloyed area around the Cr particles. So, in the case of this powder, the metallic material is not dissolved in the silver matrix but remains in the form of the primary Cr particles. There is no evidence for the dissolution of the Cr Ni particles in the matrix, otherwise the element concentration in the Ag matrix would have been possible to measure and the element would have been visible in Figure 7.  
During heating, the Ag-Ni-Cr alloy sample showed one solution with a maximum transformation temperature of 381 \({}^{\circ}\)C (Figure 9); compared to pure silver, a lower melting point was found in accordance with the TTT diagram (time-temperature-transformation) of this quaternary alloy. For the Ag-Ni-Cr alloy, the maximum temperature during heating was found to be 381 \({}^{\circ}\)C. This was lower than that for pure silver Ag 99. This was due to the presence of alloy additions in the form of chromium (Cr) and nickel (Ni), which resulted in an approximately 6.5% reduction in the transformation temperature. Detecting the drop in phase transition temperature is important for using the material in higher-temperature applications. The obtained DSC curves of the tested Ag-Ni-Cr alloy obtained during cooling (Figure 10) showed the crystallization transition temperature of the tested material in the presence of five phase transformations, where three solutions are important due to the fact that they have a relatively high transformation energy, amounting to 62 mJ, 0.9 mJ, 40.9 mJ, and 39.9 mJ, respectively (peak values of approximately 448 \({}^{\circ}\)C, 510 \({}^{\circ}\)C, and 546 \({}^{\circ}\)C). The lowest and highest transformation values (446 \({}^{\circ}\)C and 546 \({}^{\circ}\)C) are associated with the crystallization of impurities such as sulphur- and copper-containing compounds in a similar way to the cooling of pure silver Ag. In turn, the value of the transformation  
Figure 8: EDS pointwise analysis of the chemical composition performed: (**a**) Surface layer cross section of the Ag alloy, power 1.5 kW, (**b**) area of the SEM image, and (**c**) area of marked square in SEM image. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Chemical Element**} & \multicolumn{2}{c}{**Concentration, \%**} \\ \hline  & **Mass, \%** & **Atomic, \%** \\ \hline  & Point 1 & \\ \hline Ag & 100.0 & 100.0 \\ \hline Cr & 0.0 & 0.0 \\ \hline  & Point 2 & \\ \hline Cr & 76.91 & 51.83 \\ \hline Si & 2.55 & 3.19 \\ \hline O & 20.54 & 44.98 \\ \hline \hline \end{tabular}
\end{table}