## 4 Conclusions  
The results of this comparative study on the effects of thermomechanical treatment--including cold rolling (CR) with various strains ranging from moderate to severe and subsequent post-deformation annealing (PDA)--on the phase and structure states, crystallographic texture, and crystallographic limit of recovery strains of low-, medium-, and high-Zr Ti-Zr-Nb SMAs have led to the following conclusions:  
1. The intermediate cold rolling of Ti-22 Nb-6 Zr, Ti-18 Zr-15 Nb, and Ti-41 Zr-12 Nb alloys with \(e\) = 1.5 and PDA at 800 \({}^{\circ}\)C for 30 min results in the formation of fine- and coarse-grained structures. The grain size of the predominant \(\beta\)-phase increases in high-zirconium alloys. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Thermomechanical Treatment** & \(\overline{D}\), \(\mu\)**m** & \(\varepsilon_{r}{}^{max}\), \% \\ \hline
22-6 & & \\ \hline
1.5 + 600 (30) & 2.14 \(\pm\) 0.26 \(\times\) 4.47 \(\pm\) 0.61 & 2.9 \(\pm\) 0.4 \\
1.5 + 800 (30) & 21.3 \(\pm\) 1.8 & 2.7 \(\pm\) 0.4 \\
3.0 + 550 (5) & 0.15 \(\pm\) 0.01 & 2.4 \(\pm\) 0.3 \\
3.0 + 600 (5) & 0.73 \(\pm\) 0.11 & 2.3 \(\pm\) 0.3 \\ \hline
18-15 & & \\ \hline
1.5 + 600 (30) & 3.49 \(\pm\) 0.54 \(\times\) 4.49 \(\pm\) 0.61 & 5.3 \(\pm\) 0.5 \\
1.5 + 800 (30) & 8.1 \(\pm\) 0.7 \(\times\) 21.5 \(\pm\) 1.8 & 5.0 \(\pm\) 0.3 \\
3.0 + 550 (5) & 0.51 \(\pm\) 0.03 & - \\
3.0 + 600 (5) & 0.68 \(\pm\) 0.04 & 5.4 \(\pm\) 0.3 \\ \hline
41-12 & & \\ \hline
1.5 + 600 (30) & 16.3 \(\pm\) 2.4 \(\times\) 30.2 \(\pm\) 4.4 & 6.0 \(\pm\) 0.4 \\
1.5 + 800 (30) & 68.4 \(\pm\) 7.7 \(\times\) 75.1 \(\pm\) 8.2 & 6.0 \(\pm\) 0.3 \\
3.0 + 550 (5) & 0.38 \(\pm\) 0.03 & 5.7 \(\pm\) 0.6 \\
3.0 + 600 (5) & 0.43 \(\pm\) 0.03 & 6.6 \(\pm\) 0.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Crystallographic limit of recovery strain depending on the composition of the Ti-Zr-Nb alloys and the grain size. Figure 10: The influence of grain size \(\overline{D}\) on the crystallographic limit of recovery strain (\(\varepsilon_{r}{}^{max}\)) of 22-6, 18-15, and 41-12 alloys after 1.5 + 600 (30), 1.5 + 800 (30), 3.0 + 550 (5), and 3.0 + 600 (5). 2. The severe cold rolling of Ti-22 Nb-6 Zr, Ti-18 Zr-15 Nb, and Ti-41 Zr-12 Nb alloys with \(e\) = 3.0 and PDA at 550 \({}^{\circ}\)C for 5 min results in the formation of a recrystallized equiaxed predominantly ultrafine-grained structure of the \(\beta\)-phase with some low-angle boundaries inside the grains. The average grain/subgrain size \(\overline{D}\) ranges from 0.15 to 0.50 \(\upmu\)m based on the TEM bright-field images. 3. The transition of cold rolling strain from \(e\) = 1.5 to \(e\) = 3.0 results in significant grain refinement by 3-3.5 times in high-zirconium Ti-41 Zr-12 Nb alloys. Moreover, a decrease in the PDA temperature from 800 to 600 \({}^{\circ}\)C (30 min) leads to grain refinement by 1.1 to 2.2 times from low- to high-Zr alloys. 4. After \(e\) = 0.3 + 800 \({}^{\circ}\)C for 30 min, a weak favorable \(\{111\}_{\beta}\)\(<\)110\(>_{\beta}\) recrystallization texture is formed in the Ti-22 Nb-6 Zr alloy, while no texture is observed in the other alloys. After \(e\) = 1.5 + 600 \({}^{\circ}\)C for 30 min, the Ti-22 Nb-6 Zr alloy exhibits the strongest crystallographic texture \(\{111\}_{\beta}\)\(<\)110\(>_{\beta}\) compared to the Ti-18 Zr-15 Nb alloy, where the texture is weaker, and the Ti-41 Zr-12 Nb alloy, where this type of texture is not completely formed due to the partial development of recrystallization. Increasing the degree of CR to severe (\(e\) = 3.0) leads to the formation of a strong \(\{111\}_{\beta}\)\(<\)110\(>_{\beta}\) recrystallization texture after PDA in all alloys. Alloys with a low Zr content are more susceptible to this type of crystallographic texture formation during TMT, primarily due to a higher Nb content. 5. The Ti-41 Zr-12 Nb alloy has a highest crystallographic limit of recovery strain of \(\varepsilon_{r}\)\({}^{max}\)\(\approx\) 6%.