Structural and Mechanical Properties of Ti–Co Alloys Treated by High Pressure Torsion

Straumal, Boris B.; Korneva, Anna; Kilmametov, Askar; Lityńska‐Dobrzyńska, Lidia; Горнакова, А. С.; Chulist, R.; Карпов, М. И.; Zięba, P.

doi:10.3390/ma12030426

Cited by 26 publications

(17 citation statements)

References 63 publications

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“…The grains of the α-and ω-phases are visible in the microstructure. Prior to HPT, the grain size of the α-phase was several microns [26,27]. HPT leads to a strong refinement of the α-phase structure, and the grain size in the α-phase after HPT does not exceed 200 nm.…”

Section: Resultsmentioning

confidence: 99%

“…In the initial state, the Ti-4wt.% Co samples annealed near T eut contain the α-phase with a low cobalt content and the Ti 2 Co intermetallic compound (Figure 3b). The grain size of the αand Ti 2 Co-phases is approximately L = 5 µm [26,27]. After deformation, the sample contains an α-phase with a lower cobalt content ( Figure 3b) and a grain size of approximately 200 nm (Figure 1).…”

Section: Discussionmentioning

confidence: 99%

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Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

et al. 2020

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The development of next generation Ti-based alloys demand completely new processes and approaches. In particular, the Ti-alloys of next generation will contain not only α-Ti and β-Ti phases, but also small amounts of ω-phase and intermetallic compounds. The β→ω phase transformation induced by high-pressure torsion (HPT) has been studied in detail recently. In this work, we investigated the HPT-induced α→ω phase transformation. For this purpose, we added various β-stabilizers into α-Ti matrix of studied Ti-alloys. Ti-alloys with 4% Fe, 2% Cr, 3% Ni, and 4% Co (wt. %) have been annealed at the temperatures below their point of eutectoid decomposition, from β-Ti to α-Ti, and respective intermetallics (TiFe, Ti2Co, Ti2Ni, TiCr2). Volume fraction of HPT-driven ω-phase (from ≤5 up to ~80%) depended on the amount of alloying element dissolved in the α-matrix. Evaluation of lattice parameters revealed accelerated mass transfer during HPT at room temperature corresponding to bulk diffusion in α-Ti at ~600 °С.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

et al. 2020

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“…HPT leads to the transitions of α-and β-phases to the ω-phase which remain in the samples after pressure release [123][124][125][126]. The alloying of titanium with β-stabilizers (like Fe, Co or Nb) strongly modifies the α-β-ω-transformations [126][127][128][129][130]. For example, the β-to-ωtransformation in Ti-alloys is martensitic [126][127][128].…”

Section: Allotropic and Martensitic Transformationsmentioning

confidence: 99%

Diffusive and Displacive Phase Transformations Under High Pressure Torsion

Straumal

Kilmametov

Мазилкин

et al. 2019

Acta Metall Slovaca

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<p class="AMSmaintext"><span lang="EN-GB">Severe plastic deformation (SPD) can induce various phase transformations. After a certain strain, the dynamic equilibrium establishes between defects production by an external force and their relaxation (annihilation). The grain size, hardness, phase composition etc. in this steady-state does not depend on the initial state of a material and is, therefore, equifinal. In this review we discuss the competition between precipitation and dissolution of precipitates, amorphization and (nano)crystallization, SPD-induced accelerated mass-transfer, allotropic and martensitic transitions and formation of grain boundary phases.</span></p>

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“…Characterizing the mechanical properties of metals and alloys is fundamental for multiple technological applications. It is essential to depict the responses of structural components to external mechanical loadings [1,2]. Of particular interest, the investigation of titanium [3] and aluminum [4] alloys' behaviors is essential, because they are broadly used by the aerospace industry.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Commercial Purity Aluminum Modified by Zirconium Micro-Additives

et al. 2021

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The mechanical properties and the fractured surfaces of commercial purity aluminum modified by zirconium micro-additives were investigated by means of experimental examination. A commercial purity Al specimen was used as a reference material and seven Al-Zr alloys in the 0.02–0.14 wt.% Zr composition range (with 0.02 wt.% Zr step) were prepared by microalloying methods. Optical microscopy was used to examine the microstructures and to calculate the grain sizes of the prepared specimens. The phase assemblage diagrams were plotted and the relative amounts of solid phases were calculated at room temperature using FactSage thermochemical software and databases. Proof stress, strength coefficient and strain hardening exponent were measured from the stress-strain curves obtained from tensile experiments and Charpy impact energy was calculated for all specimens. The experiments showed that the grain size of commercial purity Al was reduced by adding any Zr concentration in the investigated composition range, which could be due to the nucleation of new grains at Al3Zr particle sites. Accordingly, the microhardness number, tensile properties and Charpy impact energy were improved, owing to the large grain-boundary areas resulted from the refining effect of Zr, which can limit the movement of dislocations in the refined samples. The basic fracture mode in all specimens was ductile, because Al has an FCC structure and remains ductile even at low temperatures. The ductile fractures took place in a transgranular manner as could be concluded from the fractured surface features, which include voids, ridges and cavitation.

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Structural and Mechanical Properties of Ti–Co Alloys Treated by High Pressure Torsion

Cited by 26 publications

References 63 publications

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Influence of β-Stabilizers on the α-Ti→ω-Ti Transformation in Ti-Based Alloys

Diffusive and Displacive Phase Transformations Under High Pressure Torsion

Mechanical Properties of Commercial Purity Aluminum Modified by Zirconium Micro-Additives

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