Deformation-driven formation of equilibrium phases in the Cu–Ni alloys

Straumal, Boris B.; Protasova, S. G.; Mazilkin, Andrey; Rabkin, Eugen; Goll, D.; Schütz, Gisela; Baretzky, B.; Valiev, Ruslan Z.

doi:10.1007/s10853-011-5805-0

Cited by 74 publications

(52 citation statements)

References 39 publications

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“…The torsion torque increased during 1-2 anvil rotations in all alloys and pure Ti and then remained almost unchanged. In other words, it reached a steady state, as was observed previously in other alloys [16][17][18][19][20]51,52]). The central part (about 3 mm in diameter) of each disk after HPT was excluded from further investigations (since it is low-deformed).…”

Section: Methodssupporting

confidence: 84%

“…The crystallographic mechanism of the α ↔ ω (or α ↔ β ↔ Figure 4. Pressure dependence of the volume fraction of ω-phase after HPT in pure titanium (squares) [18], Ti-2 wt % Co alloy (circles) and Ti-4% Co alloy (cross).…”

Section: Discussionmentioning

confidence: 99%

“…SPD also induces various phase transformations [12] such as formation [13][14][15] or decomposition [16][17][18][19][20] of supersaturated solid solution, dissolution of particles of a second solid phase [21][22][23][24][25][26], amorphization [27][28][29][30][31][32] and nanocrystallization [33][34][35]. Among this variety, very interesting are the phase transformations with formation of high-pressure phases.…”

Section: Introductionmentioning

confidence: 99%

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The α → ω Transformation in Titanium-Cobalt Alloys under High-Pressure Torsion

Kilmametov

Ivanisenko

Straumal

et al. 2017

Metals

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Abstract:The pressure influence on the α → ω transformation in Ti-Co alloys has been studied during high pressure torsion (HPT). The α → ω allotropic transformation takes place at high pressures in titanium, zirconium and hafnium as well as in their alloys. The transition pressure, the ability of high pressure ω-phase to retain after pressure release, and the pressure interval where α and ω phases coexist depend on the conditions of high-pressure treatment. During HPT in Bridgeman anvils, the high pressure is combined with shear strain. The presence of shear strain as well as Co addition to Ti decreases the onset of the α → ω transition from 10.5 GPa (under quasi-hydrostatic conditions) to about 3.5 GPa. The portion of ω-phase after HPT at 7 GPa increases in the following sequence: pure Ti → Ti-2 wt % Co → Ti-4 wt % Co → Ti-4 wt % Fe.

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Section: Methodssupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The α → ω Transformation in Titanium-Cobalt Alloys under High-Pressure Torsion

Kilmametov

Ivanisenko

Straumal

et al. 2017

Metals

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“…2a nd 3). The grain size d before HPT was between 50 and 500 l m [ 66,72]. After HPT the grain size d measured by TEM was about 200 nm in both Cu-4.9wt.% Co alloys (Fig.2)a nd about 150 nm in the Cu-77 wt.% Ni alloy (Fig.3).…”

Section: Resultsmentioning

confidence: 94%

Phase transitions induced by severe plastic deformation: steady-state and equifinality

Straumal

Kilmametov

Ivanisenko

et al. 2015

International Journal of Materials Research

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Durings evere plastic deformation (SPD),asteady-state is usually reached after ac ertain value of strain( i. e. number of passes duringequal-channelpressing or number of rotations during high pressure torsion). The structure and properties of amaterial in asteadystate (including composition of phases) do not depend on those in the starting state before SPD.Inother wordsthey are equifinal, and the production of lattice defects is in dynamicequilibriumwithdefect elimination. Moreover, the SPD-treatment at ambient temperature T SPD =300 Ki sf requently equivalent to the heat treatment at ac ertain elevatedt emperature T eff >300 K. For example, the composition of phases in Cu -Ni, Co -Cu and Nd -Fe-B-based alloys after high pressure torsion corresponds to the states at 200,8 90 and 1170 8 C, respectively, and is rather insensitive to the highpressure torsion rate (between 0.2 and 2r pm) and pressure (between 3a nd 8GPa).

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“…However, SPD could as well result in the decomposition of super-saturated solid solutions, such as in Al-Zn and Al-Mg [39], as well as in Cu-Ni [40], furthermore, even an under-saturated solid solution could undergo elemental separation during SPD, as reported in [26], due to the existence of large fraction of grain boundaries in nanocrystalline microstructure. It is unknown whether the mixing is still effective for a multi-component system like HEA.…”

Section: Introductionmentioning

confidence: 99%