Dynamics of self-interstitial migration in Fe-Cu alloys

Marian, Jaime; Wirth, B. D.; Perlado, J.M.; Odette, G.R.; Rubia, T. Dı́az de la

doi:10.1103/physrevb.64.094303

Cited by 48 publications

(32 citation statements)

References 18 publications

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“…The crowdion mechanism enabling the easy interstitial migration along 111 directions in V is also available in Fe, and estimates for the migration barrier ∆E d = 0.04 eV [4] are similar to the V case. However, measurements of the apparent activation energy for diffusivity, analogous to the one presented here (albeit over a smaller temperature range between 700 K and 1200 K) yield much larger values of ∆E d = 0.12 eV [16] or ∆E d = 0.17 eV [21]. This larger effective barrier is due to the fact that the 111 -split interstitial must be thermally excited from the 110 -state, i.e.…”

Section: (B)mentioning

confidence: 74%

Strongly non-Arrhenius self-interstitial diffusion in vanadium

et al. 2004

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We study diffusion of self-interstitial atoms (SIAs) in vanadium via molecular dynamics simulations. The 111 -split interstitials are observed to diffuse one-dimensionally at low temperature, but rotate into other 111 directions as the temperature is increased. The SIA diffusion is highly non-Arrhenius. At T < 600 K, this behavior arises from temperature-dependent correlations. At T > 600 K, the Arrhenius expression for thermally activated diffusion breaks down when the migration barriers become small compared to the thermal energy. This leads to Arrhenius diffusion kinetics at low T and diffusivity proportional to temperature at high T . The creation and migration of self-interstitial atoms (SIAs) are critical for microstructural evolution of materials in a variety of situations, such as in the high energy radiation environment of nuclear reactors [1] and in ion implantation [2]. Although SIA formation energies are much larger than typical thermal energies, they form in abundance during collision cascades induced by impinging energetic particles. SIAs in metals are typically very mobile (i.e., their migration barriers are relatively small) and hence play an important role in controlling the rates of many microstructural processes in such applications, in particular the phenomenon of void swelling.Since SIA properties and mobilities are very difficult to determine experimentally, one often employs computer simulations [3,4,5,6]. For example, simulations of body centered cubic (bcc) iron (and several other bcc metals), have shown that SIAs preferentially lie along 110 orientations but rotate into 111 -directions, where they can migrate easily using the crowdion configuration as transition state. Other simulations have suggested that SIA migration in vanadium is very similar to that in Fe [7,8,9,10]. However, these empirical interatomic potential-based simulations are not consistent with recent first principles calculations that clearly show that the lowest energy SIA configuration in V is a 111 -split interstitial, rather than the 110 -split configuration found in Fe [11]. Interestingly, the first principles calculations also revealed that the 111 -oriented SIA migration energy is extraordinarily small (≤ 0.01eV), which explains the experimental observation of diffusion down to 4 K [12]. SIA migration in Fe and V must therefore differ in their microscopic mechanisms.We perform a series of molecular dynamics (MD) sim- † current address: Department of Physics, Ewha Womans University, Seoul 120-750, Korea.ulation of SIA migration in V using an improved interatomic potential for V [13] (refit to experimental and first principles data [11] to reproduce the stable interstitial configuration) to address this discrepancy. In particular, we examine SIA diffusion as a function of temperature to determine the SIA migration mechanisms. We find that while SIA migration in V is similar to that in bcc Fe in many respects, its temperature dependence is highly unusual, exhibiting strongly non-Arrhenius behavior and correlation ef...

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Section: (B)mentioning

confidence: 74%

Strongly non-Arrhenius self-interstitial diffusion in vanadium

et al. 2004

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“…Although the migration barriers for the crowdion mechanism in α-Fe are also believed to be very small (< 0.04 eV), the observed effective migration barrier (including rotation into the 111 orientation and migration along the 111 -direction) are higher than in V 29,30 . Similar arguments apply to Mo and Ta.…”

Section: Introductionmentioning

confidence: 88%

Point defect dynamics in bcc metals

2005

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We present an analysis of the time evolution of self-interstitial atom and vacancy (point defect) populations in pure bcc metals under constant irradiation flux conditions. Mean-field rate equations are developed in parallel to a kinetic Monte Carlo (kMC) model. When only considering the elementary processes of defect production, defect migration, recombination and absorption at sinks, the kMC model and rate equations are shown to be equivalent and the time evolution of the point defect populations is analyzed using simple scaling arguments. We show that the typically large mismatch of the rates of interstitial and vacancy migration in bcc metals can lead to a vacancy population that grows as the square root of time. The vacancy cluster size distribution under both irreversible and reversible attachment can be described by a simple exponential function. We also consider the effect of highly mobile interstitial clusters and apply the model with parameters appropriate for vanadium and α−iron.

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“…This implies that the accumulation density of defect in BCC iron could be much lower than that in Cu. As another example, Marian et al 97,98 have used MD to study the SIA migration Fig. 2.…”

Section: Interstitials Dumbbells and Crowdionsmentioning

confidence: 99%

Molecular Dynamics Simulation of Iron — A Review

Chui

Liu

et al. 2015

SPIN

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Molecular dynamics (MD) is a technique of atomistic simulation which has facilitated scienti¯c discovery of interactions among particles since its advent in the late 1950s. Its merit lies in incorporating statistical mechanics to allow for examination of varying atomic con¯gurations at nite temperatures. Its contributions to materials science from modeling pure metal properties to designing nanowires is also remarkable. This review paper focuses on the progress of MD in understanding the behavior of iron -in pure metal form, in alloys, and in composite nanomaterials. It also discusses the interatomic potentials and the integration algorithms used for simulating iron in the literature. Furthermore, it reveals the current progress of MD in simulating iron by exhibiting some results in the literature. Finally, the review paper brie°y mentions the development of the hardware and software tools for such large-scale computations.

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Dynamics of self-interstitial migration in Fe-Cu alloys

Cited by 48 publications

References 18 publications

Strongly non-Arrhenius self-interstitial diffusion in vanadium

Strongly non-Arrhenius self-interstitial diffusion in vanadium

Point defect dynamics in bcc metals

Molecular Dynamics Simulation of Iron — A Review

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