Anelastic relaxation due to interstitial solute atoms in face-centred cubic metals

Numakura, Hiroshi; Kashiwazaki, K.; Yokoyama, Hirokazu; Koiwa, M.

doi:10.1016/s0925-8388(00)00949-x

Cited by 20 publications

(10 citation statements)

References 18 publications

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“…Indeed, to a first approximation, the peak height varies as the square of the carbon concentration, as observed in several investigations for a carbon peak in pure nickel. [14] This is an expected result given the relatively large carbon concentrations involved and reports of carbon-carbon pair binding, with binding energies of the order 5 to 10 kJ/mol, for pure nickel. [14] Note that these carbon-carbon binding energies are small compared to the C-V binding energies of about 35 to 40 kJ/mol reported in subsequent sections of this article.…”

Section: Internal Frictionmentioning

confidence: 67%

Experimental and theoretical evidence for carbon-vacancy binding in austenite

Slane

Wolverton

Gíbala

2004

Metall Mater Trans A

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Our research and results from the literature all consistently suggest a binding energy of nearest-neighbor carbon-vacancy (C-V) pairs of the order 35 to 40 kJ/mole in austenitic alloys. Results examined include point-defect anelasticity, self-diffusion, high-temperature creep, strain aging, strain-age hardening, radiation damage, and point-defect structure modeling. Increases in the height of carbon-based anelastic peaks by quenching, cold work, and electron irradiation are consistent with a substantial nonexclusive contribution of C-V complexes. Increased carbon content in austenite increases the iron self-diffusivity and the high-temperature creep rate of fcc Fe, implying a C-V binding energy of ϳ40 kJ/mol. Dynamic strain aging of carbon-containing austenites occurs in temperature ranges too low to involve interstitial solute mobility and requires an interpretation of large C-V binding wherein the vacancy is the more mobile component. Strengthening in heavily deformed austenitic stainless steels associated with strain aging or long-term aging near room temperature implies solution hardening by tetragonal-like C-V complexes formed at these temperatures. Results on radiation damage of austenitic steels show effects of carbon on irradiation susceptibility. Finally, we have performed first-principles gradient-corrected density functional calculations to determine the binding energy of nearest-neighbor C-V pairs in fcc iron; a value of ϳ35 kJ/mol is obtained.

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Section: Internal Frictionmentioning

confidence: 67%

Experimental and theoretical evidence for carbon-vacancy binding in austenite

Slane

Wolverton

Gíbala

2004

Metall Mater Trans A

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“…They, furthermore, show that this negligible level of binding is consistent with the experimental estimates of the C-C pair concentration as a function of total C concentration. 93 From the data presented above we would suggest that C-C and N-N interactions in Fe-based austenitic alloys will be repulsive at 1 nn and 2 nn, with binding energies in the range from −0.1 to −0.2 eV. We would, furthermore, expect the level of repulsion to be reduced as a function of increasing Ni concentration.…”

Section: Solute-solute Interactionsmentioning

confidence: 93%

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

et al. 2013

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An extensive set of first-principles density functional theory calculations have been performed to study the behavior of He, C, and N solutes in austenite, dilute Fe-Cr-Ni austenitic alloys, and Ni in order to investigate their influence on the microstructural evolution of austenitic steel alloys under irradiation. The results show that austenite behaves much like other face-centered cubic metals and like Ni in particular. Strong similarities were also observed between austenite and ferrite. We find that interstitial He is most stable in the tetrahedral site and migrates with a low barrier energy of between 0.1 and 0.2 eV. It binds strongly into clusters as well as overcoordinated lattice defects and forms highly stable He-vacancy (V m He n ) clusters. Interstitial He clusters of sufficient size were shown to be unstable to self-interstitial emission and VHe n cluster formation. The binding of additional He and V to existing V m He n clusters increases with cluster size, leading to unbounded growth and He bubble formation. Clusters with n/m around 1.3 were found to be most stable with a dissociation energy of 2.8 eV for He and V release. Substitutional He migrates via the dissociative mechanism in a thermal vacancy population but can migrate via the vacancy mechanism in irradiated environments as a stable V 2 He complex. Both C and N are most stable octahedrally and exhibit migration energies in the range from 1.3 to 1.6 eV. Interactions between pairs of these solutes are either repulsive or negligible. A vacancy can stably bind up to two C or N atoms with binding energies per solute atom up to 0.4 eV for C and up to 0.6 eV for N. Calculations in Ni, however, show that this may not result in vacancy trapping as VC and VN complexes can migrate cooperatively with barrier energies comparable to the isolated vacancy. This should also lead to enhanced C and N mobility in irradiated materials and may result in solute segregation to defect sinks. Binding to larger vacancy clusters is most stable near their surface and increases with cluster size. A binding energy of 0.1 eV was observed for both C and N to a [001] self-interstitial dumbbell and is likely to increase with cluster size. On this basis, we would expect that, once mobile, Cottrell atmospheres of C and N will develop around dislocations and grain boundaries in austenitic steel alloys.

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“…As they give rise to a noncubic lattice distortion, these point-defect pairs can reorient in the stress field of the partial dislocations by the single hop of the vacancy or the carbon atom to a more favorable position, effectively locking the partial dislocation. [14,15] Alternatively, the 1/6 h112i-type shear of the leading partial dislocation disturbs the original fcc stacking sequence and traps the interstitial carbon atom of the point-defect pair in a transient nonequilibrium interstitial position. The carbon atoms can be transferred back to an octahedral position within the stacking fault by a single diffusional jump, and if enough pointdefect pairs are present, they effectively make it more difficult for the trailing partial dislocation to restore the fcc lattice.…”

Section: Jinkyung Kim and Bc De Coomanmentioning

confidence: 99%

“…[16] This value is about half the value of the activation energy for carbon diffusion in c-Fe. Anelasticity due to the stress-induced reorientation of point-defect complexes in fcc steels has been ascribed to second-neighbor interstitial-interstitial solute pairs, [14,[17][18][19] interstitial-substitutional solute pairs, [14,18,20] and interstitial solute-vacancy pairs. [15,[21][22][23][24] There have been several reports indicating that whereas the nearest-neighbor C-C interaction was repulsive, the C-vacancy interaction [15,[21][22][23][24][25][26] and the C-Mn interaction [25,26] in austenitic alloys were both attractive.…”

Section: Jinkyung Kim and Bc De Coomanmentioning

confidence: 99%

On the Stacking Fault Energy of Fe-18 Pct Mn-0.6 Pct C-1.5 Pct Al Twinning-Induced Plasticity Steel

Kim

Cooman

2011

Metall Mater Trans A

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The stacking fault energy (SFE) of Fe-18 pct Mn-0.6 pct C-1.5 pct Al twinning-induced plasticity (TWIP) steel was measured using weak-beam dark-field imaging of dissociated dislocations observed in transmission electron microscopy. The SFE was found to be 30 mJ/m 2 . A relatively wide scatter was observed in the experimentally measured partial dislocation separation of screw dislocations. It is argued that the anomalously wide partial dislocation separation is due to the interaction of point-defect pairs involving interstitial C atoms with the strain field of the partial dislocations. Internal friction (IF) experiments were carried out to detect the presence of point-defect pairs that might affect the dislocation separation, and a clear Finkelshtein-Rosin (FR) peak related to point-defect pairs involving interstitial C atoms was observed in the IF spectrum.High Mn austenitic twinning-induced plasticity (TWIP) steel is one of the most promising newly developed automotive steels owing to a superior combination of strength and ductility. The stacking fault energy (SFE) is an important material property. Its value must be within a narrow range for deformationinduced twinning to occur. The SFE is determined by composition and temperature. Remy and Pineau [1] were the first to report that the two deformation modes observed in low SFE Fe-Mn fcc alloys, the occurrence of a strain-induced c fi e martensitic transformation and deformation twinning, were controlled by the composition dependence of the SFE. The critical stacking fault energy range to achieve twinning-induced plasticity is still unclear, and no experimental SFE determination is currently available for the two TWIP steel compositions that are considered to have the most industrial potential: Fe-22 pct Mn-0.6 pct C and Fe-18 pct Mn-0.6 pct C-1.5 pct Al. Frommeyer et al. [2] indicated that whereas an SFE larger than about 25 mJ/m 2 will result in the twinning effect in a stable c phase, an SFE smaller than about 16 mJ/m 2 results in e phase formation. Allain et al. [3] mentioned a much narrower range. According to them, the SFE should be at least 19 mJ/m 2 to obtain mechanical twinning. They also mentioned that an SFE less than 10 mJ/m 2 results in strain-induced e-phase formation. Dumay et al. [4] indicate that below an SFE of 18 mJ/m 2 , twinning tends to disappear and is replaced by the formation of e-platelets. They conclude that an SFE of about 20 mJ/m 2 is needed for the best hardening rate. Finally, Jin and Lee [5] indicated that an SFE value of 33 mJ/m 2 is required to obtain twinning in Fe-18 pct Mn-0.6 pct C-1.5 pct Al. In the present contribution, the authors report the first systematic measurements of the SFE of Fe-18 pct Mn-0.6 pct C-1.5 pct Al TWIP steel. In addition, it was found that for screw dislocations, the partial dislocation separation was abnormally wide. This is believed to be caused by the same point-defect complexes that cause dynamic strain aging (DSA) in TWIP steel alloyed with carbon to stabilize the austenitic structure.In the past,...

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Anelastic relaxation due to interstitial solute atoms in face-centred cubic metals

Cited by 20 publications

References 18 publications

Experimental and theoretical evidence for carbon-vacancy binding in austenite

Experimental and theoretical evidence for carbon-vacancy binding in austenite

First-principles study of helium, carbon, and nitrogen in austenite, dilute austenitic iron alloys, and nickel

On the Stacking Fault Energy of Fe-18 Pct Mn-0.6 Pct C-1.5 Pct Al Twinning-Induced Plasticity Steel

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