## 3 Results and Discussion
### Thermal Analysis of Composite Al-Nano-Al\({}_{2}\)O\({}_{3}\)  
Thermal analysis of Al-Al\({}_{2}\)O\({}_{3}\) composites was measured by a thermal analyzer STA 449C Jupiter, NETZSCH at a heating rate of 10 K/min, the temperature determination error was \(<\)1.5 K. Synchronous analysis of samples of aluminum-nano-alumina composites was carried out by differential scanning calorimetry (DSC) and thermogravimetry as a function of temperature in air atmosphere. In the first case, the sample was heated to temperatures up to 723 \({}^{\circ}\)C, cooled and, without removing the sample from the crucible, heated repeatedly to the same temperatures, and then the sample was heated to the temperature of 800 \({}^{\circ}\)C. The samples of the initial aluminum and studied composites exhibited congruent melting, since the melting peaks were reproduced during repeated cooling and heating cycles, while the lines were expressed in one DSC anomaly with the same areas during each repeated cooling/heating cycle. The onset points changed no more than 0.3 \({}^{\circ}\)C, hence the maximum temperatures, indicating the termination of the melting process of the samples, differed slightly and fluctuated in the range of 669.9-671.4 \({}^{\circ}\)C (Table 3).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**\% TiO\({}_{2}\) Added** & **T Exposure, h** & **T Interaction, \({}^{\circ}\)C** & **\% Al\({}_{2}\)O\({}_{3}\) in the Ingot** \\ \hline
0.5 & 3 & 700 & 7.8 \(\pm\) 0.2 \\ \hline
0.5 & 5 & 700 & 13.5 \(\pm\) 0.3 \\ \hline
0.5 & 3 & 750 & 4.6 \(\pm\) 0.2 \\ \hline
0.5 & 5 & 750 & 13.0 \(\pm\) 0.3 \\ \hline
1.0 & 3 & 700 & 8.2 \(\pm\) 0.2 \\ \hline
1.0 & 5 & 700 & 18.4 \(\pm\) 0.2 \\ \hline
1.0 & 3 & 750 & 8.7 \(\pm\) 0.3 \\ \hline
1.0 & 5 & 750 & 10.1 \(\pm\) 0.3 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The influence of the concentration of TiO\({}_{2}\) precursor, temperature, and exposure time on the concentration of Al\({}_{2}\)O\({}_{3}\) inside the obtained Al-Al\({}_{2}\)O\({}_{3}\) composite.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**\(\mathcal{N}\)** & **Al\({}_{2}\)O\({}_{3}\) wt.\%** & **T\({}_{ons}\)\({}^{\circ}\)C** & **T\({}_{m}\)\({}^{\circ}\)C** & **\(\Delta\)G, J/g** \\ \hline
1 & 0 & 660.3 & 669.9 & \(-\)10.63 \\ \hline
2 & 7.8 & 660.5 & 671.4 & \(-\)10.55 \\ \hline
3 & 18.4 & 660.6 & 669.4 & \(-\)10.8 \\ \hline
4 & 4.6 & 660.2 & 668.4 & \(-\)10.91 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Onset points, melting temperatures, and Gibbs energies of melting of Al-Al\({}_{2}\)O\({}_{3}\) samples.  
This phenomenon illustrates the property of peak reproducibility (Figure 7), which is a reflection of the reversibility of the phase transition during cooling and subsequent heating. The closeness of the value for the obtained composites to the parameters of the original metal can be primarily due to the indicators of the wettability of the dispersed oxide nanophase by aluminum. The data obtained by the thermogravimetry simultaneously with the differential scanning calorimetry also revealed that the thermal stability of the obtained composite materials was close to pure aluminum. The recorded change in the mass of the aluminum was equal to 0.74% and that in the composite samples during three heating and cooling cycles did not exceed 0.37%. Such an insignificant change in the mass of the sample during measurements, accompanied by the appearance of lines attributed to endothermic anomalies during DSC, directly indicated the presence of the process, which is a first-order phase transition with a high reproducibility index.