| Autor: |
Grishkov V; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Lotkov A; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Zhapova D; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Mironov Y; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Timkin V; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Barmina E; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia., Kashina O; Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia. |
| Abstrakt: |
The paper analyzes the surface structure and phase state of Ti 49.4 Ni 50.6 (at%) hydrogenated at 295 K in normal saline (0.9% NaCl aqueous solution with pH = 5.7) at 20 A/m 2 for 0.5-6 h. The analysis shows that the average hydrogen concentration in the alloy increases with the hydrogenation time t H as follows: slowly to 50 ppm at t H = 0.5-1.5 h, steeply to 150 ppm at t H = 1.2-2 h, and linearly to 300 ppm at t H = 2-6 h. According to Bragg-Brentano X-ray diffraction data (θ-2 θ, 2 θ ≤ 50°, CoKα radiation), the alloy in its scanned surface layer of thickness ~5.6 µm reveals a TiNiH x phase with x = 0.64 and x = 0.54 after hydrogenation for 4 and 6 h, respectively. The structure of this phase is identifiable as an orthorhombic hydride similar to β 1 -TiFeH 0.94 (space group Pmcm), rather than as a tetragonal TiNiH x hydride with x = 0.30-1.0 (space group I4/mmm). Time curves are presented to trace the lattice parameters and volume change during the formation of such an orthorhombic phase from the initial cubic B2 phase in Ti 49.4 Ni 50.6 (at%). |
