## 2 Metals Used in WDED and Types of Microstructure and Mechanical Properties
### Titanium-Based Alloys  
Titanium and its alloys are widely used in different applications, such as aerospace [67], automotive, and biomedical [68], because of their high strength, low weight ratio, and biocompatibility at a high cost [69]. The research on titanium-based alloys has been accentuated for decreasing the cost by changing the traditional manufacturing process to the new processes and designing the new alloy components [70]. The WDED methods are widely used for fabricating large titanium-based alloys with different components and complex structures. The mechanical properties of the different titanium-based alloys and the processing parameters and methods are shown in Table 3.  
Figure 6: Schematic of the solidification of iron-based alloy fabricated by the EBDED method with and without ultrasound [55]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Technique** & **Material** & **Process Parameters** & **Microstructure** & **Condition** & **YS (MPa)** & **UTS (MPa)** & **El (\%)** & **Hardness (GPa)** & **Reported by** \\ \hline \multirow{4}{*}{**EDEDED**} & \multirow{4}{*}{T-5A1-25a-2 ZF-40 Me-4 Cr} & Vacuum chamber, Beam current: 40-60 mA, treatment beam acceleration & Subtransus solution & & & & & \\  & & & & treatment & & & & & \\  & & & & treatment & & & & & \\  & & & & & treatment & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\ \hline \multirow{4}{*}{**EDED**} & \multirow{4}{*}{T-5A1-25a-2 ZF-40 Me-4 Cr} & Vacuum chamber, Beam current: 40-60 mA, beam acceleration voltage: 60 kV, Wire wide target & \(\alpha+\beta\) & \  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline
**Technique** & **Material** & **Process Parameters** & **Microstructure** & **Condition** & **YS (MPa)** & **UTS (MPa)** & **El (\%)** & **Hardness (GPa)** & **Reported by** \\ \hline \multirow{4}{*}{**EDEDED**} & \multirow{4}{*}{T\({}_{2}\)AlNb} & Vacuum chamber, Beam current: 60 mA, Beam acceleration voltage: 60 kV, Writing ratio ratio \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline
**Technique** & **Material** & **Process Parameters** & **Microstructure** & **Condition** & **YS (MPa)** & **UTS (MPa)** & **El (\%)** & **Hardness (GPa)** & **Reported by** \\ \hline \multirow{4}{*}{**EDEDED**} & \multirow{4}{*}{T-4A-1V} & Vacuum chamber, Beam current: 34\(\pm\) 50 mA, & & & & & & & \\  & & Beam acceleration & \(\alpha\) + \(\beta\) & - & - & 740 (90\({}^{\circ}\)) & - & 3 to 3.3 & [75] \\  & & voltage: 300 kV, Printing speed: 392 mm/min & & & & & & & \\ \hline \multirow{4}{*}{**EDEDED**} & \multirow{4}{*}{T-6A-14V} & Vacuum chamber, Beam current: 17.5-47.5 mA, & & Annealing: & Without & Without & & & \\  & & current: 17.5-47.5 mA, & & 710 \({}^{\circ}\)C for 2 h & 848 & 956.2 & 4.5 & - & [76] \\  & & beam acceleration & \(\alpha\) + \(\beta\) & cooled in & With annealing: & With annealing: & With annealing: & & \\  & & speed: 2.7-3.9 m/min & & & & & & & \\ \hline \multirow{4}{*}{**EDED**} & \multirow{4}{*}{T-6A-14V} & Vacuum chamber, Beam current: 40.5-5 mA, & & & & & & & \\  & & beam acceleration & \(\alpha\) + \(\beta\) & & 520 (0\({}^{\circ}\)) & 633 (0\({}^{\circ}\)) & 8.5 (0\({}^{\circ}\)) & - & [77] \\  & & voltage: 30 kV, Printing speed: & & & & & & & \\  & & 2.7-955 mm/min & & & & & & & \\ \hline \multirow{4}{*}{**EDEDED**} & \multirow{4}{*}{T-6A-14V} & Vacuum chamber, Beam current: 10.0 A, Beam pulse frequency: 3 Hz, & & & & & & \\  & & pulse frequency: 3 Hz, & & & & & & \\ \cline{1-1}  & & & wire feeding rate: & & & & & & \\ \cline{1-1}  & & 100 cm/min, Wire feed angle: 60\({}^{\circ}\) & & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont._The microstructure and mechanical properties of the titanium-based alloys fabricated by the WDED are related to the heating during the fabrication process. The metastable microstructures are produced by applying the temperature for fabrication by WDED methods the cooling and heating are repeated for each layer. [PERSON] et al.