Creation of submicrocrystalline structure and improvement of functional properties of shape memory alloys of the Ti-Ni-Fe system with the help of ECAP

Прокошкин, С. Д.; Belousov, M. N.; Abramov, V. Ya.; Korotitskiy, Andrey; Makushev, S. Yu.; Khmelevskaya, I. Yu.; Dobatkin, S. V.; Stolyarov, V. V.; Prokof’ev, E. A.; ZHARIKOV, A; Valiev, Ruslan Z.

doi:10.1007/s11041-007-0009-6

Cited by 9 publications

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“…The abc pressing [4,5] and equal channel angular pressing (ECAP) [1,[6][7][8] are promising methods for obtaining massive semifinished products from TiNi-based alloys with an ultrafine-grained (UFG) structure. The regularities and features of microstructure evolution in TiNi-based alloys under the action of SPD at 623-773 K are studied in a number of works: [9][10][11][12][13][14][15][16][17][18][19][20][21] after ECAP and [4,5,22,23] after abc pressing. The effect of grain-subgrain structure refinement on the mechanical and inelastic properties of these alloys after ECAP was studied in [9][10][11][12][13][14][15][16][17][18][19][20][21] and after abc pressing in [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

“…The regularities and features of microstructure evolution in TiNi-based alloys under the action of SPD at 623-773 K are studied in a number of works: [9][10][11][12][13][14][15][16][17][18][19][20][21] after ECAP and [4,5,22,23] after abc pressing. The effect of grain-subgrain structure refinement on the mechanical and inelastic properties of these alloys after ECAP was studied in [9][10][11][12][13][14][15][16][17][18][19][20][21] and after abc pressing in [22][23][24][25][26]. It was found that these methods can achieve a refinement of the grain-subgrain structure up to 100-500 nm, depending on the pressing temperature.…”

Section: Introductionmentioning

confidence: 99%

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Crystal Structure Defects in Titanium Nickelide after Abc Pressing at Lowered Temperature

et al. 2022

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The experimental results regarding the effect of warm (573 K) abc pressing with an increase in the specified true strain, e, up to 9.55, on the microstructure and crystal structure defects (dislocations, vacancies) of the Ti49.8Ni50.2 (at %) alloy are presented. It is shown that all samples (regardless of e) have a two-level microstructure. The grains–subgrains of the submicrocrystalline scale level are in the volumes of large grains. The average sizes of both large grains and subgrain grains decrease with increasing e to 9.55 (from 27 to 12 µm and from 0.36 to 0.13 µm, respectively). All samples had a two-phase state (rhombohedral R and monoclinic B19’ martensitic phases) at 295 K. The full-profile analysis of X-ray reflections of the B2 phase obtained at 393 K shows that the dislocation density increases from 1014 m−2 to 1015 m−2 after pressing with e = 1.84 and reaches 2·1015 m−2 when e increases to 9.55. It has been established by positron annihilation lifetime spectroscopy that dislocations are the main type of defects in initial samples and the only type of defects in samples after abc pressing. The lifetime of positrons trapped by dislocations is 166 ps, and the intensity of this component increases from 83% in the initial samples to 99.4% after pressing with e = 9.55. The initial samples contain a component with a positron lifetime of 192 ps (intensity 16.4%), which corresponds to the presence of monovacancies in the nickel sublattice of the B2 phase (concentration ≈10−5). This component is absent in the positron lifetime spectra in the samples after pressing. The results of the analysis of the Doppler broadening spectroscopy correlate with the data obtained by the positron annihilation lifetime spectroscopy.

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