Molecular-Dynamics Study of Self-Interstitial Diffusion in bcc-Iron

Kusunoki, Katsuyuki

doi:10.2320/matertrans.47.1906

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…The SIA diffusion of Fe itself has been often mentioned as well. 60) In addition, another strange phenomenon lies in the estimated virtual existence of ''re-solute sulfur''. According to our mechanism, as shown in Fig.…”

Section: Mechanism Of Sulfide Precipitation In Ti-added Steelmentioning

confidence: 99%

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—

Ishiguro¹,

Murayama²,

Fujita³

et al. 2009

Mater. Trans.

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This report is the second paper in three consecutive papers to know the whole sulfide precipitation in Ti-added steel by adding a new knowledge that even a trace level of copper (0.01%Cu) acts as a sulfide-former to form copper sulfide (Cu-S). The second paper focuses on the sulfide precipitation in ferrite region in Ti-added steel, especially in real-produced hot-rolled and annealed steel sheets.Although it has been believed that the sulfide precipitation is completed only in austenite region except for a few limited papers, Ti 4 C 2 S 2 , MnS and Cu-S are really formed in ferrite region. When as-hot-rolled Ti-added steel is annealed, the sulfide precipitation transforms morphologically and compositionally. The phenomenon can be explained through the same mechanism in the first paper that TiSdecomposition-induced re-solute sulfur is re-precipitated. When annealed in ferrite region, already-precipitated TiS is changed into Ti 4 C 2 S 2 and re-solute sulfur comes out along the estimated reaction ''4TiS þ 2[C] ! Ti 4 C 2 S 2 þ 2[S]'', and it is re-precipitated in ferrite region as other precipitates (Ti 4 C 2 S 2 , MnS and Cu-S). The precipitation of Cu-S is estimated to occur at the lowest temperature among re-precipitated sulfides, and therefore is affected by the precedent sulfide precipitation phenomena.

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Section: Mechanism Of Sulfide Precipitation In Ti-added Steelmentioning

confidence: 99%

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—

Ishiguro¹,

Murayama²,

Fujita³

et al. 2009

Mater. Trans.

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“…Numerous theoretical studies have been performed to obtain formation/migration energies of defects in alpha Fe by using molecular dynamics (MD) simulations, density function theory (DFT) and kinetic Monte Carlo simulations [1][2][3][4][5][6][7][8][9][10][11]. The defect kinetics are needed for multiple scale modeling of defect evolution in stainless steels for reactor applications.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of interstitial defects in α-Fe: The effect from uniaxial stress

Kang

Wang

Shao

2017

Journal of Nuclear Materials

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Understanding defect kinetics in a stress field is important for multiscale modeling of materials degradation of nuclear materials. By means of molecular dynamics and molecular statics simulations, we calculate formation and migration energies of self-interstitial atoms (SIA) and SIA clusters (up to size of 5 interstitials) in alpha Fe and identify their stable configurations under uniaxial tensile strains. By applying uniaxial stress along [111], <111> oriented single SIA defects become more stable than <110> oriented SIA, which is opposite to stress-free condition. Diffusion of single SIA defects under [111] tensile stress is facilitated along [111] direction and the diffusion becomes one dimensional (1D). For SIA clusters, their diffusion under zero stress has gradual transition from three dimensional (3D) for small clusters to one dimensional (1D) for large clusters. Under the tensile stress along [111], the 3D to 1D transition is accelerated. For large SIA clusters, the stress effect is quickly saturated with less diffusivity enhancement in comparison with small SIA clusters.

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“…Activation energy for self-interstitial formation is approximately 2 -5 x larger than for vacancy. This energy can be reduced by so called dumbbell configuration [177][178][179][180][181] in which two atoms share one lattice point; the lattice point is usually at their common center of mass. However, this is independent of the tendency of self-atom (Fe) to occupy interstitial positions and form solid solution).…”

Section: Self-interstitial Solid Solution Strengthening -Crystallogramentioning

confidence: 99%

Plasma Facing Material by Self-Interstitial Solid Solution Strengthening – Problem, Proposition, and a Solution

Rafique¹

2020

Preprint

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Bubble (point defect) – a precursor of fuzz or under dense nanostructure formation is crystal lattice defect. Suitable selection of crystal lattice which inhibit Frenkel pair generation and intrinsically promotes selfinterstitial solid solution strengthening contributes effectively towards making plasma facing material. For this, interstitial sites, their size, amount / fraction, positions, tendency of occupation and diffusion parameters (e.g. activation energies (Q), activation volumes) are determined. Fcc iron carbon alloys (austenitic stainless steels AISI / SAE 321, fcc structure, Pearson code cF4, space group Fm3̅m) are proposed as suitable candidates. Along with their room temperature fcc structure having 12 interstitial positions (4 octahedral, 6 coordination sites and 8 tetrahedral, 4 coordination sites / unit cell) to allow insertion of self (iron) atoms, they have excellent corrosion resistance, thermal conductivity, and nonmagnetic properties. After their melting, casting, and machining to required dimensions and geometry, stabilizing heat treatment is applied to precipitate all carbon as TiC and prevent formation of Cr23C6 (sensitization). This resist heat and surface degradation and yield excellent architecture which not only inhibit Frankel pair generation but will also allow bulk assimilation or surface annihilation (loop punching) of this lattice point defect. A superior thermal, fluid, and structural design augment above

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Molecular-Dynamics Study of Self-Interstitial Diffusion in bcc-Iron

Cited by 8 publications

References 13 publications

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—

Kinetics of interstitial defects in α-Fe: The effect from uniaxial stress

Plasma Facing Material by Self-Interstitial Solid Solution Strengthening – Problem, Proposition, and a Solution

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Molecular-Dynamics Study of Self-Interstitial Diffusion in bcc-Iron

Cited by 8 publications

References 13 publications

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) &mdash;Precipitation in Ferrite Region&mdash;

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) &mdash;Precipitation in Ferrite Region&mdash;

Kinetics of interstitial defects in α-Fe: The effect from uniaxial stress

Plasma Facing Material by Self-Interstitial Solid Solution Strengthening – Problem, Proposition, and a Solution

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Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (2) —Precipitation in Ferrite Region—