Study of hydrogen redistribution in Ti_49.1Ni_50.9 alloy (at %) with nanocrystalline structure by resistometric and durometer methods

The electrolytical hydrogenation of TiNi-based alloys with shape memory and super elasticity results in a significant (by 1,5 times) increase in the microhardness of the surface layer. It is shown that the change of microhardness at long-term aging at room temperature in wire samples of Ti_50,1Ni_50,9 (at %) alloy with nanocrystalline structure can be used for estimation of diffusion mobility of hydrogen. On wire samples with different diameters it is shown that the increase in the relative electrical resistance at 83K at long-term aging at room temperature for this alloy is also associated with the diffusion mobility of hydrogen. Estimates of the hydrogen diffusion coefficient D_H show that in nanocrystalline samples Ti_50,1Ni_50,9 (at %) the diffusion mobility of hydrogen is higher than in coarse-grained samples. This is connected with the increased contribution of grain boundary hydrogen diffusion in samples with nanocrystalline structure.