## 3 Results and Discussion
### Anisotropy of Tensile Properties  
#### 3.3.1 Effect of Different Frequencies of Applied Vibration  
Figure 10 compares the tensile properties of the Z- and X-direction specimens processed without applied vibration and with the application of vibrations of different frequencies. It is shown that applied vibration can significantly reduce the tensile property anisotropy of ME parts and it can further decrease the anisotropy with an increase in its frequency. Details can be found in Table 6.  
As can be seen, the average tensile strength difference between \(Z^{0}_{0}\_i\) and \(X^{0}_{0}\_i\) (\(i\) = 1-9) is 127.4%. The corresponding plasticity difference is 77.9%. For \(X^{0.1}_{100\_i}\) and \(Z^{0.1}_{100\_i}\) (\(i\) = 1-9), the difference in the two parameters is reduced to 91.4% and 62.2%, respectively. When considering \(X^{0.1}_{900\_i}\) and \(Z^{0.1}_{900\_i}\) (\(i\) = 1-9), the difference between the two values is further reduced to 43.9% and 33.3%, respectively. The reason is that when vibrations are introduced, the specimens have fewer defects and the bond between material layers becomes closer, making such specimens denser in structure with stronger adhesive strength. With increase in the vibration frequency, the forming quality of specimens is further improved, especially for the Z-direction ones. Therefore, the tensile proper  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Specimens (\(i\) = 1–9)**} & \(Z^{0}_{0}\_i\) & \(Z^{0.1}_{100\_i}\) & \(Z^{0.1}_{200\_i}\) & \(Z^{0.1}_{300\_i}\) & \(Z^{0.1}_{400\_i}\) & \(Z^{0.1}_{500\_i}\) & \(Z^{0.1}_{600\_i}\) & \(Z^{0.1}_{700\_i}\) & \(Z^{0.1}_{800\_i}\) \\ \cline{2-11}  & \(X^{0}_{0}\_i\) & \(X^{0.1}_{100\_i}\) & \(X^{0.1}_{200\_i}\) & \(X^{0.1}_{300\_i}\) & \(X^{0.1}_{400\_i}\) & \(X^{0.1}_{500\_i}\) & \(X^{0.1}_{500\_i}\) & \(X^{0.1}_{600\_i}\) & \(X^{0.1}_{700\_i}\) & \(X^{0.1}_{800\_i}\) & \(X^{0.1}_{900\_i}\) \\ \hline Average tensile strength difference (\%) & 127.4 & 91.4 & 90.2 & 85.0 & 73.3 & 67.6 & 62.6 & 60.0 & 52.3 & 43.9 \\ Average plasticity difference (\%) & 77.9 & 62.2 & 60.7 & 58.7 & 56.4 & 53.9 & 50.4 & 47.1 & 43.2 & 33.3 \\ \hline \hline \end{tabular}
\end{table}
Table 6: The tensile property anisotropy of the specimens built without applied vibration and with vibrations of different frequencies applied.  
Figure 10: Tensile property anisotropy of the specimens built without applied vibration and with different vibrations applied. (**a**) The effect of different vibrations (0.1 g amplitude with different frequencies) on the specimens’ tensile strength anisotropy and (**b**) the effect of different vibrations (0.1 g amplitude with different frequencies) on the specimens’ plasticity anisotropy.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Specimens (\(i\) = 1–9)** & \(X^{0}_{0}\_i\) & \(X^{0.1}_{700\_i}\) & \(X^{0.2}_{700\_i}\) & \(X^{0.3}_{700\_i}\) \\ \hline Average tensile strength (MPa) & 53.85 & 55.45 & 55.13 & 54.32 \\ Standard deviation & 1.99 & 1.92 & 1.86 & 1.88 \\ Growth (\%) & — & 2.97 & 2.38 & 0.87 \\ Average plasticity (\%) & 10.1 & 10.9 & 10.8 & 11.0 \\ Standard deviation & 0.53 & 0.43 & 0.46 & 0.40 \\ Growth (\%) & — & 7.92 & 6.93 & 8.91 \\ \hline \hline \end{tabular}
\end{table}
Table 5: The tensile properties of the X-direction specimens processed without applied vibration and with different applied vibrations.  
of the specimen is reduced with applied vibration and further decreased with increasing vibration frequency.