Substructural-phase transformations during heat treatments of the Ti–50.9 at % Ni nanocrystalline alloy

The method of transmission electron microscopy is used to study the grain-subgrain structure of the Ti–50.9 at % Ni nanocrystalline alloy after heat treatments at 300–500$^{\circ}$C. It is found that the decomposition of the B$_2$ solid solution of TiNi by the heterogeneous mechanism occurs in the subgrain structure, while the Ti$_{3}$Ni$_{4}$ particles are not observed in nanograins. The features of the recovery and recrystallization of the alloy and their relationship with the processes of dissolution and precipitation of Ti$_{3}$Ni$_{4}$ particles are revealed.