Grain Boundary Diffusion, Stresses and Segregation

Bokstein, Boris S.

doi:10.4028/www.scientific.net/ddf.323-325.31

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…However the dimensions of the intermetallic Ti 3 Al plates and their volume fraction significantly increased. It is obvious that with increase of hydrogenation time and hydrogen concentration in the samples, not only grain-boundary segregation of Al atoms, but also the so-called wetting phase transition takes place [43][44][45]. In other words, at the initial stage of hydrogenation, grain-boundary segregation of impurity atoms leads to the formation of solid solution of Al in α phase at small-angle boundaries.…”

Section: Sem and Tem Analysismentioning

confidence: 99%

Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

Pushilina

Панин

Сыртанов

et al. 2018

Metals

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In this paper, phase transitions and microstructure evolution in titanium Ti-6Al-4V alloy parts produced by electron beam melting (EBM) under hydrogenation was investigated. Hydrogenation was carried out at the temperature of 650 • C to the absolute hydrogen concentrations in the samples of 0.29, 0.58, and 0.90 wt. %. Comparative analysis of microstructure changes in Ti-6Al-4V alloy parts was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Furthermore, in-situ XRD was used to investigate the phase transitions in the samples during hydrogenation. The structure of Ti-6Al-4V parts produced by EBM is represented by the α phase plates with the transverse length of 0.2 µm, the β phase both in the form of plates and globular grains, and metastable α" and ω phases. Hydrogenation to the concentration of 0.29 wt. % leads to the formation of intermetallic Ti 3 Al phase. The dimensions of intermetallic Ti 3 Al plates and their volume fraction increase significantly with hydrogen concentration up to 0.58 wt. % along with precipitation of nano-sized crystals of titanium δ hydrides. Individual Ti 3 Al plates decay into nanocrystals with increasing hydrogen concentration up to 0.9 wt. % accompanied by the increase of proportion and size of hydride plates. Hardness of EBM Ti-6Al-4V alloy decreases with hydrogen content.

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Section: Sem and Tem Analysismentioning

confidence: 99%

Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

Pushilina

Панин

Сыртанов

et al. 2018

Metals

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“…During the roundtable discussion at the International Conference DSS-2010 in Moscow [81] this subject was under discussion:…”

Section: Effect Of the Gb Tension Gradientmentioning

confidence: 99%

Grain Boundary Diffusion and Grain Boundary Segregation in Metals and Alloys

Bokstein

Rodin

2014

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“…The quantities D A and D B represent the values of the tracer diffusion coefficients of components A and B in the grain boundary, respectively, for details see [3]. We would like to mention that Bokstein [31] introduced exponentially varying diffusion coefficients in the grain boundaries which increased from the bulk value to the maximal value in the middle of the grain boundaries.…”

Section: Dissipation In the Systemmentioning

confidence: 99%

Abnormal grain growth: a non-equilibrium thermodynamic model for multi-grain binary systems

Svoboda¹,

Fischer²

2013

Modelling Simul. Mater. Sci. Eng.

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Abnormal grain growth as the abrupt growth of a group of the largest grains in a multi-grain system is treated within the context of unequal retardation of grain growth due to the segregation of solute atoms from the bulk of the grains into the grain boundaries. During grain boundary migration, the segregated solute atoms are dragged under a small driving force or left behind the migrating grain boundary under a large driving force. Thus, the solute atoms in the grain boundaries of large grains, exhibiting a large driving force, can be released from the grain boundary. The mobility of these grain boundaries becomes significantly higher and abnormal grain growth is spontaneously provoked.The mean-field model presented here assumes that each grain is described by its grain radius and by its individual segregation parameter. The thermodynamic extremal principle is engaged to obtain explicit evolution equations for the radius and segregation parameter of each grain. Simulations of grain growth kinetics for various conditions of segregation with the same initial setting (100 000 grains with a given radius distribution) are presented. Depending on the diffusion coefficients of the solute in the grain boundaries, abnormal grain growth may be strongly or marginally pronounced. Solute segregation and drag can also significantly contribute to the stabilization of the grain structure. Qualitative agreement with several experimental results is reported.

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Grain Boundary Diffusion, Stresses and Segregation

Abstract: A short review of the most important reliable, as well as doubtful, in authors opinion points in a wide field of grain boundary diffusion, stresses and segregation.

Cited by 4 publications

References 20 publications

Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

Grain Boundary Diffusion and Grain Boundary Segregation in Metals and Alloys

Abnormal grain growth: a non-equilibrium thermodynamic model for multi-grain binary systems

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