## 3 Results
### Results of Statistical Analysis for the NiTi-2 Alloy
\[f_{t_{2}}^{(l)}(x)=\frac{0.0036943(0.31248+x)^{1.9765}}{\left(1+0.00124116(0.3 1248-x)^{2.9765}\right)^{2}},\ x\geq-0.31248, \tag{37}\]  
\[f_{t_{2}}^{(d)}(x)=\frac{0.00764131x^{1.488260618}}{\left(1+0.000738595x^{3.101 1}\right)^{1.80238}},\ x\geq 0, \tag{38}\]  
\[f_{t_{2}}^{(g)}(x)=0.0435831e^{-0.226203(x-1.43)}(x-1.43)^{1.0829},\ x\geq 1.43. \tag{39}\]  
The Log-Logistic, Dagum and Gamma distributions prove to be the best fitted three-parameter distributions for the tidal environment. The corresponding CDF formulas, specified by the set of the best parameter values, are shown in Equations (40)-(42). Figure 14:0  
Figure 14:1  
Figure 14:2For the three best-fitted three-parameter distributions in the case of NiTi-2 alloy and tidal environment, it can be shown that their mean values had approximately the same value as the mean corrosion rate from Equation (6). Namely, the mean values were 11.175 nm/month, 11.072 nm/month and 10.638 nm/month, respectively, while the Standard Deviations were, respectively, 9.4225 nm/month, 8.8037 nm/month and 6.3802 nm/month. PDFs and CDFs of the best fitted three-parameter distributions (Generalised Pareto, Dagum and Fatigue Life) in the case of the sea environment are shown in Equations (43)-(48), respectively. Note that, as in the previous expressions, we substituted into general expressions for distributions PDF and CDF the values of the best-fitting parameters. Figure 14:3  
Figure 14:4  
Figure 14:5  
Figure 14:6  
Figure 14:7  
Figure 14:8  
where \(\Phi[x]\) represents the Laplace integral, i.e., \(\Phi[x]=\frac{1}{\sqrt{2\pi}}\int_{0}^{x}e^{-\frac{2}{2}dt}\). The mean value of corrosion rate from Equation (7) has a very close value to all three mean values of the specified Generalised Pareto, Dagum and Fatigue Life distributions. These mean values were 23.963 nm/month, 24.853 nm/month and 23.962 nm/month, respectively, while the Standard Deviations were, 10.336 nm/month, 16.491 nm/month and 10.655 nm/month, respectively, proving the fact that these three distributions are describing well the empirical data related to the sea environment and the NiTi-2 alloy. As an example, probability estimates for related corrosion wear due to the influence of the sea environment concerning the NiTi-2 alloy can be calculated based on the best fitted Generalised Pareto PDF Equation (43) and the estimate given by Equation (10), as follows:  
Figure 14:9  
where \(t>0\) (months) is the elapsed time of the sea's influence on the NiTi-2 alloy, and \(10.585\leq c_{a}<c_{b}\leq 63.59\). For example, if \(c_{a}=11\) nm/month, \(c_{b}=13\) nm/month, and \(t=6\), 12, 18 months are taken, and these values are replaced into Equation (49), the following estimates can be calculated for probabilities:  
\[ \begin{array}{ll}P(66\ \text{nm}\leq d(6)\leq 78\ \text{nm})&=P(132\ \text{nm}\leq d(12)\leq 156\ \text{nm})\\ &=P(198\ \text{nm}\leq d(18)\leq 234\ \text{nm})\\ &=\int\limits_{11}^{13}0.0559(1-0.0189(x-10.585))^{1.96226}dx=0.106.\end{array}  \tag{50}\]  
In the case of the NiTi-2 alloy we used the same approach as in the case of the NiTi-1 alloy, to address the goodness-of-fit. Namely, Kolmogorov-Smirnov and Anderson-Darling tests were used to determine the three best fitted theoretical distributions which can describe monthly corrosion rate adequately in each observed seawater environment. The results of these tests for the air environment are shown in Table 12.  
Table 12 has the same structure as Table 8, and it shows details of the goodness-of-fit tests for the NiTi-2 alloy in the air environment. KS and AD tests were employed to check the goodness-of-fit of the selected best-fitted three-parameter theoretical distributions for all observed seawater environments in the case of the NiTi-2 alloy. The results related to these tests in the case of the air environment are presented in Table 12. Both statistical tests were performed with the same values of significance level (\(\alpha=0.05,\ 0.02,\) and \(0.01\)).