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The regularities and features of the evolution of the grain–subgrain structure, phase composition and mechanical properties in Ti_49.8Ni_50.2 (at.%), depending on the temperature of isochronous annealings at 573–973 K are herein studied. The state of the Ti_49.8Ni_50.2 (at.%) alloy samples after <i>abc</i> pressing at T = 573 K with the given true strain <i>e</i> = 9.55 was taken as the initial state. It is shown that the grain–subgrain structure of the samples after annealing for 1 h in the temperature range of 573–673 K changes slightly. In samples annealed at 673 K, regions with the microband structure similar to the microstructure of a fast-frozen turbulent liquid flow were found. It has been established that during annealing at 773 K the beginning of an active recrystallization process is realized; the size of grains does not exceed the submicrocrystalline scale (~200 nm). At 873 K, the recrystallization process occurs in the entire volume of the samples; the grains with an average size of 2 ± 0.5 µm are almost equiaxed. The microstructure of the samples after annealing at 973 K (with average grain sizes of 5 ± 0.5 µm) is qualitatively similar to the microstructure of the samples after annealing at 873 K. It was found that the phase composition of the samples as a result of isochronous annealing at 573–973 K changes from R and B19’ immediately after <i>abc</i> pressing to a three-phase state: B2, R and B19’ phases. It is shown that the highest values of yield stress σ_y, ultimate tensile strength σ_UTS (1043 MPa and 1232 MPa, correspondingly) and low ductility (the deformation to fracture ε_f = 48%) are observed in the initial samples. Increasing the temperature of post-deformation annealing and, correspondingly, the development of recrystallization, led to a decrease in σ_y, σ_UTS and an increase in ε_f to the values of these characteristics in the coarse-grained samples (σ_y = 400 MPa, σ_UTS = 920 MPa and ε_f = 90%).