The effect of athermal and isothermal ω phase particles on elasticity of β-Ti single crystals

Nejezchlebová, Jitka; Janovská, Michaela; Seiner, Hanuš; Sedlák, Petr; Landa, Michal; Šmilauerová, Jana; Stráský, Josef; Harcuba, Petr; Janeček, Miloš

doi:10.1016/j.actamat.2016.03.033

Cited by 51 publications

(18 citation statements)

References 25 publications

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“…This positive variation is indicative of solute transfer from the matrix to α" iso , as discussed by Banumathy et al [46]. It is also important to highlight that the value of c α" lattice parameter at the onset of precipitation,~4.56 Å (Figure 7b), is close to the a parameter of the ω phase, a ω ,~4.55 Å ( Table 1); this proximity is an indicator that the formation of α" iso may be directly related to ω decomposition [3,9,37,38]. This, together with the fact that the volume fraction of α + α" iso grows whilst β (with some presence of ω) decomposes (Figure 7a) may indicate that precipitation of α + α" iso occurs due to the homogenization of domains resulting from spinodal decomposition of β.…”

Section: Precipitation and Decomposition Of α" Isomentioning

confidence: 56%

“…The formation of such dislocations results in the distortion of β matrix lattice, hence its contribution is more significant to peak broadening, i.e., to the FWHM [33]. The difficulties for detection of ω phase are also reported for HEXRD studies [33,34]; nevertheless, recent observations carried out by high-energy small angle X-ray scattering during ageing in single crystals of metastable β titanium alloys could determine the presence and evolution of this phase [35][36][37]. Figure 6 shows the hardness evolution during ageing.…”

Section: In Situ Measurementsmentioning

confidence: 99%

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In Situ Analysis of the Phase Transformation Kinetics in the β-Water-Quenched Ti-5Al-5Mo-5V-3Cr-1Zr Alloy during Ageing after Fast Heating

Guimarães

Callegari

Warchomicka

et al. 2020

QuBS

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Thermal treatments are the main route to achieve improvements in mechanical properties of β-metastable titanium alloys developed for structural applications in automotive and aerospace industries. Therefore, it is of vital importance to determine phase transformation kinetics and mechanisms of nucleation and precipitation during heat treatment of these alloys. In this context, the present paper focuses on the assessment of solid-state transformations in a β-water-quenched Ti-5Al-5Mo-5V-3Cr-1Zr alloy during the early stages of ageing treatment at 500 °C. In situ tracking of transformations was performed using high-energy synchrotron X-ray diffraction. The transformation sequence β + ω → α + α”iso + β is proposed to take place during this stage. Results show that isothermal α” phase precipitates from ω and from spinodal decomposition domains of the β phase, whereas α nucleates from ω, β and also from α” with different morphologies. Isothermal α” is considered to be the regulator of transformation kinetics. Hardness measurements confirm the presence of ω, although this phase was not detected by X-ray diffraction during the in situ treatment.

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Section: Precipitation and Decomposition Of α" Isomentioning

confidence: 56%

Section: In Situ Measurementsmentioning

confidence: 99%

In Situ Analysis of the Phase Transformation Kinetics in the β-Water-Quenched Ti-5Al-5Mo-5V-3Cr-1Zr Alloy during Ageing after Fast Heating

Guimarães

Callegari

Warchomicka

et al. 2020

QuBS

View full text Add to dashboard Cite

show abstract

“…Moreover, formation of the ω-phase might be enhanced in dynamic conditions (during deformation) [17]. The increased volume fraction of the ω-phase has an immense effect on the macroscopic modulus of elasticity [7]. It is therefore suggested that the increase of the elastic modulus was caused by growth of the ω-phase particles.…”

Section: Resultsmentioning

confidence: 99%

“…The particles of this ω ath phase are small (in nanoscale range) and coherent with the parent β matrix [6]. During aging at temperatures in the range of 150 • C to 350 • C the ω-particles become stabilized by diffusion process -this phase is being referred to as ω iso (ω isothermal) [4,7]. * corresponding author; e-mail: annaterynkova@gmail.com Severe plastic deformation by equal channel angular pressing (ECAP) was applied as a method of grain refinement [8].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Ti-15Mo Alloy Prepared by ECAP

et al. 2018

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Metastable beta titanium alloys are perspective materials for use in biomedicine due to their excellent mechanical and physical properties, which can be improved by severe plastic deformation by reducing grain size and inserting a high degree of deformation. Ti-15Mo alloy was subjected to 1-4 passes of equal channel angular pressing in a die with channels intersecting at an angle of 120 • at the temperature of 250 • C. The microstructure observed by means of electron backscatter diffraction showed deformed and highly twinned structure, but the deformation was not sufficient for achieving an ultrafine grained material. The microhardness increased with the increasing number of equal channel angular pressing passes. The Young modulus was measured by the methods of resonant ultrasound spectroscopy and also increased with the number of equal channel angular pressing passes. Significant increment of elastic modulus can be attributed to the formation ω-phase particles.

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“…the calculation of the second order tensor (third order square matrix) of elastic strain components ε kl from the matrix of stress components σ ij and the fourth order tensor of compliance constants, S ijkl (inverse of the elastic constants tensor, C ijkl ). Values of elastic constants for both phases are available in the literature [23,24]. Equation 12account for the calculation of tensors of elastic strain components ε F kl , ε G kl by means of elastic deformation gradients (atomic shifts caused by the elastic deformation), F el in the ω def phase and G el in the β phase, I is the identity matrix.…”

Section: Criteria For the ω Def Phase Formationmentioning

confidence: 99%

Modeling of the Formation of Stress-Induced ω Phase in Metastable β Titanium Alloys

et al. 2018

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Titanium alloys are materials with exceptional properties including high specific strength, extreme corrosion resistance, and biocompatibility. Among them, metastable β titanium alloys are a prospective group exhibiting complex phase transformations which can be employed to improve the performance of the material. Microstructural mechanisms controlling phase transformations in these alloys are not completely understood. In this work, we propose a continuum-based model describing non-diffusional, displacive, reversible β → ω phase transformation which leads to a formation of stress-induced ω def phase. The proposed model utilizes a well-developed mathematical theory of martensitic phase transitions based on the Cauchy-Born hypothesis, and reformulates this theory to describe the crystallographic mechanism of β → ω def phase transformation. The model evaluates compatibility criteria at the interfaces between β and ω def phases in relation to the external stress and provides conditions for the formation of ω def phase.

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The effect of athermal and isothermal ω phase particles on elasticity of β-Ti single crystals

Cited by 51 publications

References 25 publications

In Situ Analysis of the Phase Transformation Kinetics in the β-Water-Quenched Ti-5Al-5Mo-5V-3Cr-1Zr Alloy during Ageing after Fast Heating

In Situ Analysis of the Phase Transformation Kinetics in the β-Water-Quenched Ti-5Al-5Mo-5V-3Cr-1Zr Alloy during Ageing after Fast Heating

Microstructure and Mechanical Properties of Ti-15Mo Alloy Prepared by ECAP

Modeling of the Formation of Stress-Induced ω Phase in Metastable β Titanium Alloys

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