Effect of thermal cycling in the range of phase transformation B2-B19’ on the microstructure and mechanical properties of UFG alloy Ti49.8Ni50.2

Churakova, Anna; Gunderov, D. V.; Lukyanov, A.; Lebedev, Yu. A.

doi:10.22226/2410-3535-2013-2-166-168

Cited by 4 publications

(3 citation statements)

References 2 publications

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“…It is of special interest to establish the influence of the UFG state of TiNi alloys on the structural changes during thermal cycling through martensitic transformation temperatures, to determine the role of grain boundaries in dislocation generation at phase martensitic transformations, and to establish the possibility of mechanical and functional properties enhancement of these materials via phase hardening. There are a limited number of publications on studies of thermal cycling influence on UFG TiNi alloys [11][12][13]. However, the paper [11] is devoted mainly to the effect of mechanocycling on ECAP-processed TiNi.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

et al. 2019

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Influence of thermomechanical treatment (deformation, thermal cycling treatment in the temperature range of martensitic transformations B2-B19’) on the TiNi alloys’ mechanical behaviour and fracture was studied. Different states were considered, they are initial coarse-grained (CG), ultrafine-grained (UFG) after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% - UFG state with high dislocation density. It was shown that thermal cycling causes some increase in dislocation density, strength and microhardness in all the states. Thermal cycling of UFG alloys allows forming the states with non-equilibrium grain boundaries, with additional dislocations of “phase hardening”. The nature of the fracture was analysed in the TiNi alloy in various states.

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Section: Introductionmentioning

confidence: 99%

“…There are a limited number of publications on studies of thermal cycling influence on UFG TiNi alloys [11][12][13]. However, the paper [11] is devoted mainly to the effect of mechanocycling on ECAP-processed TiNi. The papers [12,13] mainly deal with the issues of dilatation in UFG TiNi alloys during thermal cycling.…”

Section: Introductionmentioning

confidence: 99%

Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

et al. 2019

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“…Unlike the majority of other known materials with martensitic transformations (steels, etc. ), the temperatures of martensitic transformations in TiNi are close to the room one, that is why thermal cycling does not lead to recrystallization of UFG and NC structures [10]. In this connection, TiNi is an interesting object to study the effects of the UFG and NC states, the grain size and increased area of the grain boundaries on phase hardening resulting from thermal cycling.…”

Section: Introductionmentioning

confidence: 99%

Transformation of the TiNi Alloy Microstructure and the Mechanical Properties Caused by Repeated B2-B19′ Martensitic Transformations

Churakova

Гундеров

Lukyanov

et al. 2015

Acta Metall. Sin. (Engl. Lett.)

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The influences of thermal cycling treatment in the temperature range of B2-B19 martensitic transformations (-150 to 150°C) on the TiNi alloy structure and properties were studied. Different states named the initial coarse-grained (CG) state, the ultrafine-grained (UFG) state after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% were considered. The results show that the microhardness and the strength increase in all the three states. According to the XRD analysis, a more significant increment in the dislocation density, resulting from thermal cycling, is observed in the UFG alloy than in the CG alloy.

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Effect of True Strains in Isothermal abc Pressing on Mechanical Properties of Ti49.8Ni50.2 Alloy

Кашин

Круковский

Лотков

et al. 2020

Metals

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The paper analyzes the microstructure and mechanical properties of Ti49.8Ni50.2 alloy (at.%) under uniaxial tension at room temperature after isothermal abc pressing to true strains e = 0.29−8.44 at T = 723 K. The analysis shows that as the true strain e is increased, the grain–subgrain structure of the alloy is gradually refined. This leads to an increase in its yield stress σy and strain hardening coefficient θ = dσ/dε at linear stage III of its tensile stress–strain curve according to the Hall–Petch relation. However, the ultimate tensile strength remains invariant to such refinement. The possible mechanism is proposed to explain why the ultimate tensile strength can remain invariant to the average grains size (dav). It is assumed that the sharp increase of the ultimate tensile strength σUTS begins when (dav) is less than the critical average grain size (dav)cr. In our opinion, for the investigated alloy (dav)cr ≈ 0.5 µm. In our study, the attained average grain size is larger the critical one. The main idea of the mechanism is next. In alloys with an average grain size (dav) less than the critical one, a higher external stress is required for the nucleation and propagation of the main crack.

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Effect of thermal cycling in the range of phase transformation B2-B19’ on the microstructure and mechanical properties of UFG alloy Ti49.8Ni50.2

Cited by 4 publications

References 2 publications

Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

Transformation of the TiNi Alloy Microstructure and the Mechanical Properties Caused by Repeated B2-B19′ Martensitic Transformations

Effect of True Strains in Isothermal abc Pressing on Mechanical Properties of Ti49.8Ni50.2 Alloy

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