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°C. It is found that the decomposition of the B2 solid solution of TiNi by the heterogeneous mechanism occurs in the subgrain structure, while the Ti3Ni4 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 Ti3Ni4 particles are revealed.