On the mechanism of sulfur fast diffusion in 3-D transition metals

Lomaev, I. L.; Novikov, D.L.; Okatov, S. V.; Gornostyrev, Yu. N.; Cetel, A.; Maloney, Michael J.; Montero, R.; Burlatsky, S. F.

doi:10.1016/j.actamat.2013.12.021

Cited by 18 publications

(17 citation statements)

References 30 publications

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Section: Vacancy-mediated Diffusionsupporting

confidence: 64%

“…Ni is similar to that of S, which is known as a fast diffuser in fcc Ni according the experimental data [68] and a recent DFT study [64]. The study reports remarkably low ω 1 and ω 2 migration barriers and strong vacancy binding calculated by first-principles DFT [64]. Note that phosphorus is typically recognized as a detrimental impurity in nickel-based superalloys and hence its nominal composition is generally specified at less than 0.015 wt.% in industrial applications.…”

Section: Vacancy-mediated Diffusionsupporting

confidence: 54%

“…These solutes demonstrate either relatively weaker vacancy-solute interaction or even slight repulsion [63]. One element showing stronger vacancy-solute binding is S (sulfur) with a binding energy of −0.42 eV [64]. Note that the 3sp-nonmetal impurities (Si, P, and S) in fcc Ni follows the relative order of vacancy binding magnitude:…”

Section: Thermo-kinetic Parameters Of Dilute Ni-p Calculated By Firstmentioning

confidence: 99%

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Ab initio study of phosphorus effect on vacancy-mediated process in nickel alloys – An insight into Ni2Cr ordering

Young

Tucker

2019

Acta Materialia

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The development of long range order in nickel-chromium alloys is of great technological interest but the kinetics and mechanisms of the transformation are poorly understood. The present research utilizes a combined computational and experimental approach to elucidate the mechanism by which phosphorus accelerates the ordering rate of stoichiometric Ni 2 Cr in Ni-Cr alloys. A series of Ni-33%Cr-x%P samples (in atomic percent) were fabricated with phosphorus concentrations, x = <0.005-0.1 at.% and aged between 373 and 470°C for times up to 3000 h.The first-principles modeling considers fcc Ni with dilute P as a reasonable approximation for the complex Ni-Cr-P alloy system. Calculation results show a pronounced enhancement of vacancy transport by vacancy-solute pair diffusion via consecutive exchange and rotation jumps of vacancies associated with the phosphorus atom. The energy barriers of these two migration paths are at least 0.35 eV lower than that of vacancy-atom exchange in pure Ni solvent. The analytical diffusion model predicts enhanced solvent diffusion by 2 orders of magnitude for 0.1 at.% P at 400-500°C. The model prediction is in good agreement with the evolution of micro-hardness.We characterize the micro-hardness result by a kinetic ordering model, showing a significant decrease of the activation energy of ordering transformation. These results help gauge the risk of industrial alloys developing long range order which increases strength but degrades ductility and toughness. Specifically, minor alloying additions that bind with excess vacancies and lower the vacancy migration barrier can greatly accelerate hardening via Ni 2 Cr precipitation.

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Section: Vacancy-mediated Diffusionsupporting

confidence: 64%

Section: Vacancy-mediated Diffusionsupporting

confidence: 54%

Section: Thermo-kinetic Parameters Of Dilute Ni-p Calculated By Firstmentioning

confidence: 99%

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Ab initio study of phosphorus effect on vacancy-mediated process in nickel alloys – An insight into Ni2Cr ordering

Young

Tucker

2019

Acta Materialia

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“…Authors [30] suggest that nonequilibrium segregation of phosphorus in Ni-base superalloys realise via vacancy non-dissociation mechanism, when a vacancy moves around a P atom without loss of bonding due to a high binding energy of a vacancy-P atom complex. The strong interaction of vacancies in 3d-metals with 3sp-solute atoms (S, P), though they are undersized impurities, is testified by data on fast diffusion of this elements [3,31]. In [31,32] it is shown that features of the electronic structures and chemical bonding in the vicinity 3sp-solute atoms play crucial role in the enhanced diffusion via vacancy mediated mechanism, rather than the atomic size mismatch.…”

Section: Resultsmentioning

confidence: 93%

“…The strong interaction of vacancies in 3d-metals with 3sp-solute atoms (S, P), though they are undersized impurities, is testified by data on fast diffusion of this elements [3,31]. In [31,32] it is shown that features of the electronic structures and chemical bonding in the vicinity 3sp-solute atoms play crucial role in the enhanced diffusion via vacancy mediated mechanism, rather than the atomic size mismatch.…”

Section: Resultsmentioning

confidence: 93%