## 2 Materials and Methods  
Ti-22 Nb-6 Zr, Ti-18 Zr-15 Nb, and Ti-41 Zr-12 Nb (at.%) SMAs were chosen as target materials for a comprehensive study of TMT effects on structure formation. Laboratory-size 250 g ingots were obtained by vacuum arc melting with a non-consumable tungsten electrode in an Arcasr arc200 furnace (Arcast Inc., Oxford, ME, USA). To improve the quality and homogeneity of the ingots, each was obtained with six consequent re-melts. The composition of the main elements was checked by EDS analysis on a Tescan Vega3 SBH microscope (TESCAN, Brno, Czech Republic): all elements were near the target composition within the method's sensitivity range (Table 1). Impurity contents were measured by a high-temperature gas extraction technique using a TC-600 analyzer (Leco, Geleen, The Netherlands). All the ingots had a low impurity content, with the highest impurity contents being (wt.%) O--0.1700 \(\pm\) 0.0020%, N--0.001%, H--0.0050 \(\pm\) 0.0004%, and C--0.027 \(\pm\) 0.002%. To remove the cast structure and improve the composition homogeneity, all ingots were cut using EDM into 55 \(\times\) 10 \(\times\) 65...70 mm billets and subjected to hot rolling with a true strain of \(e\) = 0.3 at 900 \({}^{\circ}\)C for the 22-6 and 18-15 alloys, and at 600 \({}^{\circ}\)C for the 41-12 alloy. Before the hot rolling, the billets were heated for 30 min at rolling temperature in an air atmosphere. The specific rolling temperature for the 41-12 alloy was selected in an attempt to minimalize oxidation due to the high reactivity of zirconium. After the hot deformation, all alloys were homogenization-annealed at 900 \({}^{\circ}\)C for 30 min in an argon atmosphere and then water-quenched. The resulting alloy microstructures are shown in Figure 1. After casting, the alloys have coarse grains with a size up to 1000 \(\upmu\)m, which can be elongated in the crystallization direction and then deformed by hot rolling. The hot rolling and subsequent homogenization annealing start the polygonization and recrystallization processes. The 22-6 alloy, after such treatment, exhibits a recrystallized structure with a grain size from 70 to 150 \(\upmu\)m with traces of the as-cast grain boundaries (Figure 1a). Such traces are almost invisible in the 18-15 alloy, whose structure consists of recrystallized grains ranging from 50 to 250 \(\upmu\)m and not-yet-recrystallized areas (Figure 1b). In 41-12, the initial grains are still presented, and some new grain boundaries are visible inside them, indicating the beginning of the recrystallization process. The recrystallized grains have sizes ranging from 20 to 100 \(\upmu\)m (Figure 1c). Next, the alloys were subjected to TMT, which included CR and PDA, to form different grain structure states. These states had an average \(\beta\)-phase grain size of less than 1 \(\upmu\)m (ultrafine-grained structures), 1 to 5 \(\upmu\)m (fine-grained structures), or approximately 10 \(\upmu\)m or more (coarse-grained structures). The billets were then cut using EDM into plates with thicknesses of 0.75, 1.5, and 10 mm. The choice of these plate thicknesses was to ensure a uniform specimen thickness of 0.5 mm for all CR strains. The plates were subsequently cold-rolled with true strains \(e\) = 0.3, 1.5, and 3.0. They were annealed at 550-800 \({}^{\circ}\)C for 5-30 min in an argon atmosphere and then water-cooled. The processing routes for the \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Alloy (Designation)** & **Ti** & **Zr** & **Nb** \\ \hline Ti-22 Nb-6 Zr (22-6) & Main & 22.1 & 6.3 \\ \hline Ti-18 Zr-15 Nb (18-15) & Main & 18.4 & 15.2 \\ \hline Ti-41 Zr-12 Nb (41-12) & Main & 41.2 & 12.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of the obtained ingots from the EDS analysis (at. %). studied alloys are presented in Table 2. The selection of deformation strains was based on the previous work conducted on 18-15 [25]. After the TMT, plates of 22-6, 18-15 and 41-12 alloys were cut using EDM into specimens for structure, phase composition, and texture analyses.