A crystallographic model of vacancy-supersaturation of the high-temperature b.c.c. modification of titanium

Скотникова, М. А.

doi:10.1007/bf02467470

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…The highest total boride layer thicknesses were achieved at 950°C for Cp-Ti and Ti-6Al-4V. This was explained with ‘anomalous’ diffusion that a vacancy supersaturated ω phase forms and promotes diffusion near β -transus [18,19]. Interstitial elements like oxygen are α- stabilisers and can increase the phase transition temperature with increasing solute content.…”

Section: Resultsmentioning

confidence: 99%

Boriding behaviour of titanium alloys with different crystalline structures

Kara

Pürçek

2019

Surface Engineering

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The objective of this study is to investigate the boriding behaviour of titanium implant materials on the basis of their crystalline structure and chemical composition. α-type Cp-Ti, α + β type Ti-6Al-4V and β-type Ti-45Nb alloys have been borided by the powder-pack boriding technique at temperatures between 850 and 1200°C. The X-ray diffraction, GDOES and SEM analysis demonstrated that boride layers on Cp-Ti and Ti-6Al-4V alloy mainly composed of TiB 2 and TiB phases, whereas Ti-45Nb alloy consists of the mixture of TiB 2 .NbB 2 and TiB phases. Boride layers on Ti-45Nb alloy grew uniformly and the highest boride layer thickness of 72.1 μm was obtained on this alloy among the others. Activation energies of boron in monolithic layer of Cp-Ti and Ti-6Al-4V alloy were determined to be 214.5 and 231.8 kJ/mol, respectively. Activation energies in monolithic and total boride layers on Ti-45Nb were determined to be 228.5 and 145.8 kJ/mol, respectively.

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Section: Resultsmentioning

confidence: 99%

Boriding behaviour of titanium alloys with different crystalline structures

Kara

Pürçek

2019

Surface Engineering

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“…In addition, the higher concentration of substitution vacancies in the Ti substrate near the phase transition temperature can promote the increase of B diffusion through the substitution mechanism. In fact, previous studies have also shown [36] that the ω phase formed near the transition temperature may be a vacancy supersaturated phase, which tends to promote substitution diffusion near the phase transition temperature. Based on these, it can be reasonably assumed that B atoms diffuse through the substitution sites in Ti at a speed comparable to Ti itself.…”

Section: Modeling Of Layer Growth Kineticsmentioning

confidence: 98%

Improvement of Mechanical, Tribological, and Fricative Reduction Properties of Pure Titanium by Boriding

Chen

Koyama

2021

Applied Sciences

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Surface boriding of pure titanium was performed using dissolved salt impregnation to modify the surface hardness and improve wear performance. The effect of boriding temperature (950–1150 °C) on the microstructure, composition, and room-temperature tribological properties of the borided samples was investigated by X-ray diffraction, scanning electron microscopy, and ball-on-disc tribometry, respectively. Gibbs free energy was also calculated to evaluate the compounds generated during the boriding at different temperatures. After a detailed analysis of the crystal structures and the growth morphologies of TiB, the diffusion mechanisms for B atoms in TiB and TiB2 were discussed in the present report. The boriding temperature had a large effect on the microstructure, mechanical properties, and room-temperature tribological behavior of the borided samples, attributed to the changes in the composition and the increased hardened layer under elevated boriding temperature. The modeling of layer growth kinetics was also discussed in this paper. The actual value of hardened layer thickness was compared to the calculated value, and the difference was analyzed. The fricative value of the borided samples showed a minimum value of 88.9 dB for a boriding temperature of 1050 °C. The depth and width of the wear tracks decreased gradually with increasing boriding temperature. The worn surface of the samples borided at higher temperatures showed very good wear resistance. A boriding condition of 1050 °C was considered optimal, as it provided sufficiently high surface hardness and a low fricative value to reduce vibrations during practical use.

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“…α-solid solutions decay goes through the stages of microbundling, the formation of coherent predispositions (Θ / ) and isolation of particles of a new Θphase. In the works [22][23][24][25] it is shown that a decrease in the relative elongation and contraction took place at the stage of completion of the microbinding of solid solutions and the formation of microblasts enriched in those impurity atoms that prevailed in the newly formed phase.…”

Section: New Materials and Technologies In Mechanical Engineeringmentioning

confidence: 99%

Effect of Severe Plastic Deformation on the Structure and Properties of the Aluminum Alloy System Al-Cu-Mg

Paitova

Bobruk

Shasherina

et al. 2019

KEM

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The structure and properties of discs from cast coarse-grained D16 alloy have been investigated with the help of optical metallography and transmission electron microscopy, after the traditional heat treatment (HT) modes or subjected to high pressure torsion (HPT) under pressure in 6 GPa at room temperature. Standard HT modes included: Т4 (hardening 495°С + natural aging at room temperature for 5 days) and Т6 (hardening 495°С + artificial aging at 185°С for 10 hours). It is shown that after HT of alloy D16 according to modes T6 and Т4, the sizes of the structural elements, compared with the original, decreased by about 4,8 times and the microhardness increased by 1,6 times. It is shown that after one or ten rotates of HPT in D16 alloy the sizes of structural elements, in comparison with initial, decreased by 393 and 899 times, and microhardness increased by 2,4 and 2,9 times, respectively. Detection of hardening hard, brittle and high-alloy copper γ2- phases (Cu9Al4) indicates the passage in the HPT process of the decomposition of a supersaturated solid solution (dynamic aging) in the planes of a local shift.

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A crystallographic model of vacancy-supersaturation of the high-temperature b.c.c. modification of titanium

Cited by 4 publications

References 3 publications

Boriding behaviour of titanium alloys with different crystalline structures

Boriding behaviour of titanium alloys with different crystalline structures

Improvement of Mechanical, Tribological, and Fricative Reduction Properties of Pure Titanium by Boriding

Effect of Severe Plastic Deformation on the Structure and Properties of the Aluminum Alloy System Al-Cu-Mg

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