Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Barnard, Leland; Cunningham, N.J.; Odette, G.R.; Szlufarska, Izabela; Morgan, Dane

doi:10.1016/j.actamat.2015.03.014

Cited by 47 publications

(31 citation statements)

References 73 publications

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“…contradicted by both first principles calculations, limited measurements and atomistic models fit to NO precipitation and coarsening data [52]. However, use of the cited parameter set is within the spirit of the simple model presented here.…”

Section: Discussion: Stability Of Nos Under Irradiationmentioning

confidence: 90%

Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

Aydoğan

Almirall

Odette

et al. 2017

Journal of Nuclear Materials

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A nanostructured ferritic alloy (NFA), in the form of thin-walled tubing, was fabricated by hydrostatic extrusion of a mandrel mounted mother tube cut from a plate. The plate was processed by high energy ball milling of Fe-Y-Ti-O gas atomized and FeO powders, consolidated by hot extrusion, followed by hot cross rolling. The tube microstructure is dominated by an ultrahigh density of nm-scale Y-Ti-O complex oxide precipitates. Here, we examine the stability of the nano-oxides (NOs) under 3.5 MeV Fe +2 irradiations up to a peak dose of 1100 dpa at 450 °C. Transmission electron microscopy (TEM) and atom probe tomography (APT) show that severe ion irradiation may result in a slight decrease in the average diameter and increase in the number density of the NOs. This 'inverse coarsening' can be rationalized by the competition between radiation driven ballistic dissolution and diffusional NO reformation. No significant changes in the composition of the matrix or NOs were observed after irradiation. Modeling the experimental results also indicated a slight dissolution of the particles.

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Section: Discussion: Stability Of Nos Under Irradiationmentioning

confidence: 90%

Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

Aydoğan

Almirall

Odette

et al. 2017

Journal of Nuclear Materials

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“…and, e) the solubility of Y both in the matrix and at dislocations [52], that mediates the truly remarkable long-term, high-temperature thermal stability of NOs, as modeled by cluster dynamics methods [27].…”

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confidence: 99%

The crystal structure, orientation relationships and interfaces of the nanoscale oxides in nanostructured ferritic alloys

Ciston

Kräemer

et al. 2016

Acta Materialia

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The capability of nanostructured ferritic alloys (NFAs) to manage high levels of transmutation product helium will help resolve one of the grand challenges to transforming the promise of C-free fusion energy into a reality. NFAs are dispersion strengthened by an ultrahigh density of Y-Ti-O nano-oxides (NOs), which result in both high strength and temperature limits, as well as unique irradiation tolerance. Here, aberration-corrected high-resolution transmission electron microscopy was used to characterize the NOs in four NFA conditions, including following severe deformation and extreme neutron radiation exposure. Fast Fourier Transform analysis of focal series images revealed the NO crystal structure, including the smallest at < 2 nm in diameter, to be Y 2 Ti 2 O 7 pyrochlore in all cases, consistent with both exit wave analysis and scanning transmission Z-contrast imaging of the atomic columns in a larger feature. The faceted NOs exhibit a quasi-epitaxial orientation relationship with the ferrite matrix: [110] YTO ||[100] Fe and [001] YTO ||[010] Fe , forming a 5x7 near coincidence site interface. The NOs also exhibit size-dependent strains in both the oxide and matrix ferrite phases. . The authors would like to thank M. Libbee and C. Song for their support on TEM sample preparation and training at the Molecular Foundry. Finally, we acknowledge the assistance of M. Toloczko at PNNL in providing the irradiated MA957 characterized in this study and S. Maloy at LANL and D. Hoelzer at ORNL for their role as UCSB collaborators in developing FCRD NFA-1.1

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“…Y 2 O 3 , Y 2 TiO 5 , Y 2 Ti 2 O 7 , and TiO 2 36. Their structure characteristics are summarized in Table S2.…”

Section: Resultsmentioning

confidence: 99%

“…With regard to this fact, the formation of various Y and Ti oxide phases during solidification process was thermodynamically investigated. According to literature, three ternary oxide phases of Y 2 TiO 5 , Y 2 Ti 2 O 7 , and fluorite-type solid solution (FSS) exist in TiO 2 -Y 2 O 3 system3536. The FSS phase is a stoichiometric compound with the composition of 45 mol% TiO 2 in the TiO 2 -Y 2 O 3 system i.e.…”

Section: Thermodynamic Modelmentioning

confidence: 99%

Development of an oxide-dispersion-strengthened steel by introducing oxygen carrier compound into the melt aided by a general thermodynamic model

Moghadasi

Nili‐Ahmadabadi

Forghani

et al. 2016

Sci Rep

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In general, melting process is not a common method for the production of oxide dispersion strengthened (ODS) alloys due to agglomeration and coarsening of oxide particles. However, vacuum casting process has recently been employed as a promising process to produce micro-scale oxide dispersed alloys. In this paper, we report the process and characterization of in situ formation and uniform dispersion of nano-scale Y-Ti oxide particles in Fe-10Ni-7Mn (wt.%) alloy. The processing route involves a solid-liquid reaction between the added TiO2 as an oxygen carrier and dissolved yttrium in liquid metal leading to an optimal microstructure with nano-sized dispersed oxide particles. The developed thermodynamic model shows the independence of the final phase constituents from experimental conditions such as melting temperature or vacuum system pressure which offers a general pathway for the manufacture of oxide dispersion strengthened materials.

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Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Cited by 47 publications

References 73 publications

Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

The crystal structure, orientation relationships and interfaces of the nanoscale oxides in nanostructured ferritic alloys

Development of an oxide-dispersion-strengthened steel by introducing oxygen carrier compound into the melt aided by a general thermodynamic model

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