The Evolution of the Microstructure and System of Ti3Ni4 Particles upon Heat Treatments of a Ti−50.9 at % Ni Nanocrystalline Alloy.

The structure of a Ti−(50.9 at % Ni) nanocrystalline alloy is studied by transmission electron microscopy after annealing at 300−500°C. It is found that B2-TiNi solid solution decomposition according to a heterogeneous mechanism with formation of Ti₃Ni₄ particles develops in the subgrain structure and is suppressed in nanograins. The regularities of recovery, polygonization, and recrystallization in the grain/subgrain structure of a nanocrystalline TiNi alloy are established and their interconnection with processes of dissolution and coagulation of Ti₃Ni₄ particles is identified. [ABSTRACT FROM AUTHOR]