## 3 Results and Discussion  
### Element Composition and Microstructure  
A picture of the as-deposited TiNiCu single wall structure is displayed in Figure 5. The as-prepared cross-section of the TiNiCu deposition was analyzed by Helios SEM in both the element composition and phase distribution. At each location, large area EDS was applied for element composition study. The atomic compositions of Ti, Ni, and Cu regarding the location from H1 up to H5 are plotted in Figure 6. From Figure 6, all three elements have some variations along with BD. Ti and Cu start with a composition higher than the as-mixed composition in the powder state and decrease gradually when the location rises. In contrast, Ni begins with a lower composition and gradually increases. At higher locations, the composition of the three elements becomes much closer to the initial as-mixed composition Ti50 Ni45 Cu5. The element deviation at the lower height might be due to a combined effect of dilution from the Ti substrate and powder flow rate difference among different types of metal powders [35]. SEM images were obtained for detailed analysis in microstructure and phase composition. Figure 7 is a combination of images of all five locations. Among the ten sub-images, Figure 7a,c,e,g,i are SEM images of locations H1, H2, H3, H4, and H5, respectively. Figure 7a,c,e,g,i shows the overall phase distribution, and Figure 7b,d,f,h,j shows higher magnified SEM images of a specific region within Figure 7a,c,e,g,i for small area EDS analysis on phases, respectively. As shown in Figure 7a,c,e,g, locations H1, H2, H3, and H4 are all dominated by the light gray phase as the matrix phase and the dark gray phase as the secondary phase,  
Figure 5: Image of the as-deposited TiNiCu single wall on Ti substrate. Figure 6: Ti, Ni, and Cu element composition distribution along with the height locations. which disperses within the matrix. In general, it can also be seen that the area covered by the dark gray phase decreases as the height increases. In Figure 7i, another light phase that is brighter than the matrix is also detected. In Figure 7b,d,f,h,j, ten areas within these three types of phases were picked for the EDS analysis. Areas 1, 3, 5, 7, and 9 were selected within the matrix of five height locations, while Areas 2, 4, 6, and 8 were located inside of darker secondary phases at the locations H1, H2, H3, and H4, respectively. At the height of H5, Area 10 was drawn within the brighter secondary phase. All EDS analysis results of the ten areas are listed in Table 1. In those EDS results, the relation between the atomic percentage ratio of Ti and the sum of Ni and Cu is noticed. The ratio of atomic composition Ti/(Ni + Cu) values is close to 1 in all matrices, which reveals that all five matrices are recognized as the TiNi phase with a small amount of Cu substitution. In Areas 1, 3, and 5, the matrix Ti composition exceeds 50 at.%, which is considered the Ti-rich TiNi phase, while matrix phases in Areas 7 and 9 are Ti-poor. Areas 2, 4, 6, and 8 are inside the darker secondary phase, and their Ti/(Ni + Cu) ratios are all close to 2. Then, the suggested phase will be the Ti\({}_{2}\)Ni type intermetallic phase, which includes the Cu that replaces a low percentage of the Ni as well. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Area No.** & **Ti at.\%** & **Ni at.\%** & **Cu at.\%** \\ \hline
1 & 51.2 & 38.4 & 10.4 \\
2 & 66.3 & 29.6 & 4.1 \\
3 & 51.4 & 40.9 & 7.7 \\
4 & 67.3 & 30.2 & 2.5 \\
5 & 51.0 & 42.8 & 6.2 \\
6 & 64.6 & 31.5 & 3.9 \\
7 & 49.4 & 45.8 & 4.9 \\
8 & 63.9 & 33.1 & 3.0 \\
9 & 48.2 & 46.2 & 5.6 \\
10 & 35.3 & 42.7 & 21.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The EDS results of ten selected areas in Figure 7.  
Figure 7: _Cont._  
Area 10 is selected from the inner part of the brighter phase generated at the near-top location H5 of the single wall. The EDS result in Table 1 gives that Ti at.% = 35.3%, Ni at.% = 42.7%, and Cu at.% = 21.9%.