The paper studies the interaction between hydrogen and the multiphase Ti–Ni alloy of near-equiatomic composition after its high-energy mechanical activation in a planetary ball mill generating a centrifugal acceleration of 60 g. It is described that mechanical activation results in a non-monotonous change in the average size of particles due to their destruction followed by agglomeration. After mechanical activation for 10 seconds, the width of X-ray lines changes in all phases. It is found that during the hydrogenation process, the crystal lattice parameters of the TiNi (austenite) and TiNi3 phases do not change, in contrast to the Ti2Ni phase, whose lattice parameter increases by 2.5%. This fact suggests that the main hydrogen interaction in multiphase Ti–Ni alloys of near-equiatomic composition occurs with the Ti2Ni phase. Hydrogenation of the multiphase Ti–Ni alloy powder changes the lattice parameter of the Ti2Ni phase, such that it matches the lattice parameter of the Ti2NiH0.5 and Ti2NiH0.8 hydride phases after mechanical activation for 30 and 300 seconds, respectively. The paper identifies the critical time of the defect accumulation during high-energy mechanical activation. With increasing time of hydrogenation, oxide layers destroy, thereby facilitating the hydrogen penetration into powders.
ASJC Scopus subject areas
- Physics and Astronomy(all)