The α→ω and β→ω phase transformations in Ti–Fe alloys under high-pressure torsion

2018 ◽  
Vol 144 ◽  
pp. 337-351 ◽  
Author(s):  
A.R. Kilmametov ◽  
Yu. Ivanisenko ◽  
A.A. Mazilkin ◽  
B.B. Straumal ◽  
A.S. Gornakova ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Ω Phase ◽  
Fe Alloys

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

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2262
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Alena Gornakova ◽  
Anna Wierzbicka-Miernik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Phase Transformations ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Transmission Electron ◽  
Different Temperatures

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.

Phase Transformations in Ti-Fe Alloys Induced by High-Pressure Torsion

2015 ◽  
Vol 17 (12) ◽  
pp. 1835-1841 ◽  
Author(s):  
B. B. Straumal ◽  
A. R. Kilmametov ◽  
Yu. Ivanisenko ◽  
A. S. Gornakova ◽  
A. A. Mazilkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Fe Alloys

The α↔ω phase transformations and thermal stability of Ti Co alloy treated by high pressure torsion

2021 ◽  
Vol 173 ◽  
pp. 110937
Author(s):  
A. Korneva ◽  
B.B. Straumal ◽  
A.R. Kilmametov ◽  
Ł. Gondek ◽  
A. Wierzbicka-Miernik ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Ω Phase ◽  
Thermal Stability Of

In Situ Observation of the Phase Transformations in Ti15Mo Alloy Deformed by High Pressure Torsion

2018 ◽  
Vol 385 ◽  
pp. 206-211
Author(s):  
Miloš Janeček ◽  
Kristina Bartha ◽  
Josef Stráský ◽  
Jozef Veselý ◽  
Veronika Polyakova ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Solution Treatment ◽  
Thin Foil ◽  
Scanning Calorimetry ◽  
Β Phase ◽  
Ω Phase ◽  
In Situ Heating

Metastable β-Ti alloys including Ti15Mo alloy are perspective candidates for use in medical applications. During thermal treatment Ti15Mo alloy undergoes various phase transformations. After solution treatment it contains metastable β-phase and ω-phase. During annealing the ω-phase partially dissolves as well as stable α-phase particles are formed. The solution treated Ti15Mo alloy was deformed by high pressure torsion (HPT) at room temperature. Significant grain refinement with grain size of ~100 nm was achieved even after 1/4 of HPT rotation. The effect of the ultra-fine grained (UFG) structure achieved by HPT on the phase transformations was studied by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) during in-situ heating. High density of lattice defects, dense network of grain boundaries as well as ongoing recovery and recrystallization upon heating significantly affected the phase transitions. Observation of the microstructure during in-situ heating in TEM revealed no representative changes in transparent part of the sample due to the “thin foil effect”.

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

2021 ◽  
pp. 1-7
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Lidia Lityńska-Dobrzyńska ◽  
Robert Chulist ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Chemical Compositions ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Nb Content ◽  
Long Time

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.

Effect of Deformation by High Pressure Torsion on the Phase Composition and Microhardness of Mechanically Alloyed and Rapidly Quenched Al–Fe Alloys

2003 ◽  
Vol 216-217 ◽  
pp. 313-322 ◽  
Author(s):  
Victor V. Tcherdyntsev ◽  
S.D. Kaloshkin ◽  
E.A. Afonina ◽  
I.A. Tomilin ◽  
Yu.V. Baldokhin ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Composition ◽  
High Pressure Torsion ◽  
Mechanically Alloyed ◽  
Fe Alloys

Transformation Pathway upon Heating of Ti-Fe Alloys Deformed by High-Pressure Torsion

2018 ◽  
Vol 20 (4) ◽  
pp. 1700933 ◽  
Author(s):  
Mario J. Kriegel ◽  
Askar Kilmametov ◽  
Martin Rudolph ◽  
Boris B. Straumal ◽  
Alena S. Gornakova ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Transformation Pathway ◽  
Fe Alloys

Phase Transformations in MgH 2 –TiH 2 Hydrogen Storage System by High‐Pressure Torsion Process

2019 ◽  
Vol 22 (1) ◽  
pp. 1900027 ◽  
Author(s):  
Kouki Kitabayashi ◽  
Kaveh Edalati ◽  
Hai‐Wen Li ◽  
Etsuo Akiba ◽  
Zenji Horita
Keyword(s):  
High Pressure ◽  
Hydrogen Storage ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Storage System ◽  
Hydrogen Storage System

Phase transformations in a Cu Cr alloy induced by high pressure torsion

2016 ◽  
Vol 114 ◽  
pp. 151-156 ◽  
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Robert Chulist ◽  
Piotr Straumal ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion
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