## 4 Discussion  
The proposed methods overcame the problems detected to make an accurate determination of the DCP temperature. The determination of the DCP point is very simple and done with a good accuracy in comparison to previous methods, with only one thermocouple, promoting an increased productivity with a low cost in the data analysis. There is a similar tendency in the DCP values in all the methods in relation to the variation of the alloy composition. Methods 1, 3, and 4 show a tendency to have higher DCP temperatures values because the acceleration of the cooling rate is the basis of defining the exact point at which the DCP starts in these methods, where a limited number of dendrites touch one to another, but promote the increase of the cooling rate in the sample. The rest of the methods are based on the determination of the exact moment when the cooling speed is constant, so all the dendrites touch one to another. From the studied methods, we estimate that method 6 and method 7 could be the ones with the better trend accuracy due to the fact that the use of the derivative curves plotted versus temperature is not as influenced by the size of the thermal analysis test samples on the registration curves as the  
Figure 10: The effect of the Si percentage over the dendrite coherency point temperature with method 7. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Method.** & **Si** & **Mg** & **Fe** & **Cu** & **Ni** & **Cr** & **Mn** & **Ti** & **Zn** & **Pb** & **Sn** & **Sr** \\ \hline
1 & **13.57** & 1.17 & 1.22 & 0.39 & 0.79 & 0.6 & 0.18 & 2.65 & 0.56 & 0.16 & 1.42 & 0.4 \\
2 & **11.95** & 0.57 & 0.99 & 0.35 & 1.02 & 1.17 & 0.51 & 0.37 & 1.45 & 0.42 & 0.03 & 0.61 \\
3 & **14.23** & 0.6 & 1.2 & 0.37 & 0.07 & 0.69 & 0.2 & 1.97 & 0.58 & 0.32 & 1.18 & 0.85 \\
4 & **14.09** & 0.42 & 1.11 & 0.2 & 0.35 & 0.67 & 0.51 & 1.44 & 1.09 & 0.6 & 0.87 & 0.37 \\
5 & **10.65** & 0.4 & 0.67 & 0.08 & 0.52 & 0.69 & 0.4 & 0.3 & 1.01 & 0.29 & 0.19 & 0.8 \\
6 & **11.16** & 0.38 & 0.45 & 0.08 & 0.72 & 0.64 & 0.04 & 0.38 & 1.54 & 0.52 & 0.15 & 0.57 \\
7 & **15.45** & 0.56 & 0.1 & 0.94 & 0.39 & 0.37 & 0.11 & 1.19 & 2.01 & 0.57 & 0.58 & 1.18 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The student “t” coefficients for T\({}_{\rm DCP}\). temperature, which is a thermodynamically extensive property. Additionally, very similar values were obtained from both methods. In the case of method 3, where the dT/dt curve is plotted vs. T with the DCP point in the elbow, and method 4, in which the dfs/dT curve vs. T exists with the DCP point in the elbow, there is no clear indication of which one is the exact point and it is also very complicated to obtain a curve showing a perfect elbow. The only element that has a direct effect in the studied alloys with a significant statistical influence over the TDCP is Si, with a lower impact than the other alloying elements. The increase in the percentage of Si promotes a decrease in TDCP. This is an expected behavior because it is well known that an increase in the Si% decreases the solidification interval of hypoeutectic aluminum alloys and their related characteristic solidification temperatures until the minimum solidification temperature interval is reached by eutectic composition [24]. The obtained formulae should be taken as trend indicators [25] and, taking this into account, Ni and Zn show a tendency to decrease the TDCP. It is known that an increase in the Zn% decreases the characteristic solidification temperatures of hypoeutectic aluminum alloys because the Zn enters into the solid dissolution in the alloy matrix and not into the grain boundary, avoiding the enrichment of Zn into the remaining inter-dendritic liquid metal.