Effect of the Temperature of Megaplastic Deformation in a Bridgman Chamber on the Formation of Structures and the Physicochemical Properties of Titanium (BT1-0)

Shurygina, N. A.; Черетаева, А. О.; Glezer, A. M.; D’yakonov, D. L.; Chshetinin, I. V.; Сундеев, Р.В.; Tomchuk, A. A.; Muradimova, L. F.

doi:10.3103/s1062873818090204

Cited by 15 publications

(3 citation statements)

References 26 publications

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“…The TEM observations of microstructure showed the presence of small grains of rounded shape and large grains of irregular shape with distinctive streaky contrast. The morphology of the large grains is similar to the ω-phase (Shurygina et al, 2018), while the small grains probably belong to the α-phase. The microstructure of the HPT-deformed Ti-10 wt%Nb and Ti-20 wt%Nb alloys is similar to that described above.…”

Section: Resultsmentioning

confidence: 84%

The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

et al. 2021

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The study of the fundamentals of the α → ω and β → ω phase transformations induced by high-pressure torsion (HPT) in Ti–Nb-based alloys is presented in the current work. Prior to HPT, three alloys with 5, 10, and 20 wt% of Nb were annealed in the temperature range of 700–540°C in order to obtain the (α + β)-phase state with a different amount of the β-phase. The samples were annealed for a long time in order to reach equilibrium Nb content in the α-solid solution. Scanning electron microscope (SEM), transmission electron microscopy, and X-ray diffraction techniques were used for the characterization of the microstructure evolution and phase transformations. HPT results in a strong grain refinement of the microstructure, a partial transformation of the α-phase into the ω-phase, and a complete β → ω phase transformation. Two kinds of the ω-phase with different chemical compositions were observed after HPT. The first one was formed from the β-phase, enriched in Nb, and the second one from the almost Nb-pure α-phase. It was found that the α → ω phase transformation depends on the Nb content in the initial α-Ti phase. The less the amount of Nb in the α-phase, the more the amount of the α-phase is transformed into the ω-phase.

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Section: Resultsmentioning

confidence: 84%

The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

et al. 2021

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“…High-magnification TEM observations of the microstructure ( Figure 6 ) showed small grains of rounded shape and large grains of irregular shape with distinctive streaky contrast. The morphology of the large grains was similar to the ω-phase [ 39 ], while the small grains belong to the α-phase. This was confirmed by electron diffraction analysis of the selected area, presented in Figure 7 b.…”

Section: Resultsmentioning

confidence: 99%

Omega Phase Formation in Ti–3wt.%Nb Alloy Induced by High-Pressure Torsion

et al. 2021

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It is well known that severe plastic deformation not only leads to strong grain refinement and material strengthening but also can drive phase transformations. A study of the fundamentals of α → ω phase transformations induced by high-pressure torsion (HPT) in Ti–Nb-based alloys is presented in the current work. Before HPT, a Ti–3wt.%Nb alloy was annealed at two different temperatures in order to obtain the α-phase state with different amounts of niobium. X-ray diffraction analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied for the characterisation of phase transitions and evolution of the microstructure. A small amount of the β-phase was found in the initial states, which completely transformed into the ω-phase during the HPT process. During HPT, strong grain refinement in the α-phase took place, as did partial transformation of the α- into the ω-phase. Therefore, two kinds of ω-phase, each with different chemical composition, were obtained after HPT. The first one was formed from the β-phase, enriched in Nb, and the second one from the α-phase. It was also found that the transformation of the α-phase into the ω-phase depended on the Nb concentration in the α-Ti phase. The less Nb there was in the α-phase, the more of the α-phase was transformed into the ω-phase.

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“…Therefore, the application of the HPT process and additional annealing is very promising for the development of advanced metallic biomaterials with high levels of mechanical properties. Currently, a small number of works are dedicated to the influence of the ω-Ti on the mechanical behavior of the SPD-treated alloys, where generally the hardness and Young's modulus are usually measured [24,25,36,[41][42][43], while there are practically no data on the tensile strength. The next step of our work will be to study the effect of the α→ω and ω→α phase transformations on the mechanical properties (i.e., strength and ductility) of alloys after HPT and after HPT with low-temperature annealing, determined in a tensile experiment.…”

Section: Alloymentioning

confidence: 99%

Formation and Thermal Stability of the ω-Phase in Ti–Nb and Ti–Mo Alloys Subjected to HPT

et al. 2022

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This paper discusses the features of ω-phase formation and its thermal stability depending on the phase composition, alloying element and the grain size of the initial microstructure of Ti–Nb and Ti–Mo alloys subjected to high-pressure torsion (HPT) deformation. In the case of two-phase Ti–3wt.% Nb and Ti–20wt.% Nb alloys with different volume fractions of α- and β-phases, a complete β→ω phase transformation and partial α→ω transformation were found. The dependence of the α→ω transformation on the concentration of the alloying element was determined: the greater content of Nb in the α-phase, the lower the amount of ω-phase that was formed from it. In the case of single-phase Ti–Mo alloys, it was found that the amount of ω-phase formed from the coarse-grained β-phase of the Ti–18wt.% Mo alloy was less than the amount of the ω-phase formed from the fine α′-martensite of the Ti–2wt.% Mo alloy. This was despite the fact that the ω-phase is easier to form from the β-phase than from the α- or α′-phase. It is possible that the grain size of the microstructure also affected the phase transformation, namely, the fine martensitic plates more easily gain deformation and overcome the critical shear stresses necessary for the phase transformation. It was also found that the thermal stability of the ω-phase in the Ti–Nb and Ti–Mo alloys increased with the increasing concentration of Nb or Mo.

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Effect of the Temperature of Megaplastic Deformation in a Bridgman Chamber on the Formation of Structures and the Physicochemical Properties of Titanium (BT1-0)

Cited by 15 publications

References 26 publications

The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

Omega Phase Formation in Ti–3wt.%Nb Alloy Induced by High-Pressure Torsion

Formation and Thermal Stability of the ω-Phase in Ti–Nb and Ti–Mo Alloys Subjected to HPT

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