## 3 Results and Discussion
### Mechanical Characterization of the Hybrid Coupons Based on the Small Punch Tests
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Reference**} & \multicolumn{3}{c}{\(R_{m}\) **(MPa)**} & \multicolumn{3}{c}{\(R_{p0.2}\) **(MPa)**} \\ \cline{2-6}  & **Average** & **Deviation** & **Average** & **Deviation** \\ \hline
100\% DED-LB & Measured by SPT & 798 & 52 & 524 & 28 \\ \hline
100\% WROUGHT & Measured by SPT & 981 & 38 & 895 & 116 \\ \hline
50\% DED-LB + & Measured by SPT & 848 & 6 & 606 & 7 \\
50\% WROUGHT & Weighed estimation (50/50) & 890 & - & 710 & - \\ \hline
20\% DED-LB + & Measured by SPT & 899 & 7 & 698 & 16 \\
80\% WROUGHT & Weighed estimation (20/80) & 944 & - & 821 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: SPT results obtained for Inconel 718 for the conditions studied: average value and standard deviation measured by SPT and an estimation of the results, taking into account the percentage of hybridized technology and the experimental results for pure DED-LB and pure wrought samples. Figure 9: SPT \(F\)–\(\
u\) characteristic curve for each condition. The best mechanical properties were obtained for the 100% wrought condition, while the lowest ones were obtained for the 100% DED-LB sample. It is well known that high mechanical properties can be achieved by additive manufacturing methods, but their mechanical properties are, in general, lower than those obtained for wrought products with a similar chemical composition, as is observed in the present work. The DED-LB technique is susceptible to generating defects such as oxides and pores in the deposited materials. These defects could compromise the performance of the final part, as also seen in the present work. The impact of this effect is amplified when additional layers are applied, since the higher the number of layers, the higher the risk of having defects. Figure 11: Cross-sections of fractured SPT samples extracted from positions indicated in Figure 4a. (**a**) Pos. 1: 100% filler material, (**b**) Pos. 2: 100% wrought base material, (**c**) Pos. 3: 50% filler and 50% base material, and (**d**) Pos. 4: 20% filler and 80% base material. Figure 10: Estimation of the yield strength and tensile strength from the SPTs for the hybrid Inconel 718 tests coupons compared with pure DED-LB and pure wrought samples. The better performance of the wrought material could be also related to the absence of Laves phases in the wrought material. Laves phases are formed due to segregation during solidification and are known to impair the mechanical properties [32]. However, it has been reported that they can be eliminated mostly by adequate post-heat treatments [33]. Thus, an optimized post-heat treatment will probably enhance the mechanical properties of the DED-LB material. It is worth noting that the results obtained in the SPTs that included the joining section (50% wrought + 50% DED-LB and \(\sim\)80% wrought + 20% DED-LB) are both higher than the results for the pure DED-LB sample. Thus, the joining area is not the weak point. Therefore, it can be concluded that the Inconel 718 overlay processed via DED-LB on the wrought base adheres correctly. Figure 12: Cross-sections of fractured SPT samples extracted from positions indicated in Figure 4a. (**a**) Pos. 1: Fracture in the filler material, (**b**) Pos. 2: Fracture in the wrought base material, (**c**) Pos. 3: Fracture occurs in the filler material, and (**d**) Pos. 4: Fracture occurs in the base material, (**e**) in the filler material (Pos. 1) Laves phases are observed in the interdendritic spaces and (**f**) while the base material shows the presence of small NbC carbides (Pos. 2). The estimated values in Table 3, obtained by weighting the SPT experimental results, overestimate the experimental results by 40-45 MPa for \(R_{m}\) (-5%) and by 100-125 MPa for \(R_{p0.2}\) (-17%). This means that the DED-LB contribution to the mechanical properties is slightly higher than expected by the mixed percentage of materials in the analyzed area.