Ti3Ni4 precipitation in heat-treated nanocrytalline Ti - 50.9 at. % Ni alloy

The structure of a nanocrystalline Ti-50.9 at. % Ni alloy with mixed subgrain/nanograin structure is investigated by transmission electron microscopy after annealing at temperature 400°C. The size, morphology and distribution of Ti₃Ni₄ particles formed in the process of the decomposition of a TiNi B2 solid solution are investigated. It is shown that the Ti₃Ni₄ particles precipitate in the substructure in the low-angle boundaries regions. The precipitation of coherent particles in subgrains is possible with the latter sizes less than 100 nm. At the same time, precipitations of Ti₃Ni₄ particles are not observed inside the nanograins.