Morphology, structure, and chemistry of nanoclusters in a mechanically alloyed nanostructured ferritic steel

Brandes, M.C.; Kovařík, Libor; Miller, M.K.; Mills, Michael J.

doi:10.1007/s10853-012-6249-x

Cited by 86 publications

(56 citation statements)

References 53 publications

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“…The material used in the present study was the ultrafine-grained 14YWT NFA with a nominal composition of Fe-14Cr-0.16W-0.4Ti-0.14Y-0.4O (at.%) (see alloy synthesis in Methods). Atom probe tomography and transmission electron microscopy characterizations showed that the 14YWT NFA has a grain size of 200-400 nm and contains a high number density of Y-Ti-O NCs (1-2 nm in diameter) inhomogeneously distributed in the grains and along the grain boundaries 4,17 . As the alloy was made by hot-extrusion of mechanically alloyed powders, the 14YWT NFA tensile specimen exhibits a strong o1104 fibre texture, as seen from the neutron diffraction patterns and also consistent with the texture characterization in earlier works 18 .…”

Section: Resultsmentioning

confidence: 99%

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Temperature-dependent elastic anisotropy and mesoscale deformation in a nanostructured ferritic alloy

Stoica

Miller

et al. 2014

Nat Commun

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Nanostructured ferritic alloys are a new class of ultrafine-grained oxide dispersionstrengthened steels that have promising properties for service in extreme environments in future nuclear reactors. This is due to the remarkable stability of their complex microstructures containing numerous Y-Ti-O nanoclusters within grains and along grain boundaries. Although nanoclusters account primarily for the exceptional resistance to irradiation damage and high-temperature creep, little is known about the mechanical roles of the polycrystalline grains that constitute the ferritic matrix. Here we report an in situ mesoscale characterization of anisotropic responses of ultrafine ferrite grains to stresses using state-ofthe-art neutron diffraction. We show the experimental determination of single-crystal elastic constants for a 14YWT alloy, and reveal a strong temperature-dependent elastic anisotropy that leads to elastic softening and instability of the ferrite. We also demonstrate, from anisotropy-induced intergranular strains, that a deformation crossover exists from lowtemperature lattice hardening to high-temperature lattice softening in response to extensive plastic deformation.

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Section: Resultsmentioning

confidence: 99%

“…Moreover, these NCs have been characterized to be coherent with the ferrite matrix 5,17 . Such a small volume fraction, together with the nanocluster-matrix coherency, would give rise to negligibly small misfit strains and stress concentrations, if any, between NCs and the ferrite matrix during elastic deformation.…”

Section: Discussionmentioning

confidence: 99%

Temperature-dependent elastic anisotropy and mesoscale deformation in a nanostructured ferritic alloy

Stoica

Miller

et al. 2014

Nat Commun

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“…Because of the lower diffusion coefficient, austenitic ODS alloys show a better creep resistance for the same oxide volume fraction and contain some minimum chromium/ aluminium content to guarantee sufficient oxidation resistance. However, the resistance to the coarsening of oxides is given by the product of the solubility of oxygen in the matrix and its diffusion coefficient; 16 this factor is more advantageous for ferritic ODS alloys. Also, a sufficient content of Al and/or Cr in the ODS alloy is decisive for its oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] This is probably the reason why the application of ferritic ODS steels dominates. [15][16][17][18][19][20][21][22][23] The new ODS alloys consist of a ferritic Fe-Al matrix strengthened with about 6 to 10 % volume fractions of Al 2 O 3 particles. 24,25 In order to get a more detailed insight into these new groups of materials, an experimental programme was carried out to better understand their processing behaviour and their operational properties.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of new ODS alloys under single and multiple deformation

Mašek¹,

Khalaj²,

Nový³

et al. 2016

Mater. Tehnol.

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The application of innovative processing techniques to conventional raw materials can lead to new structural materials with specific mechanical and physical properties, which open up new possibilities of use in some areas of industry. The processing is enabled by powder metallurgy, which utilizes powders consisting of a metal matrix with dispersed stable particles achieved by mechanical alloying and their hot consolidation by rolling. New oxide dispersion strengthened (ODS) Fe-Al-based alloys are tested under different single and multiple thermomechanical treatments at different temperatures. The results show that new ODS alloys are significantly affected by the thermo-mechanical treatment, leading to microstructural changes. Their analysis is performed using different analytical methods such as optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Keywords: ODS alloys, composite, steel, Fe-Al Uporaba inovativnih tehnik preoblikovanja na obi~ajnih materialih lahko privede do novih konstrukcijskih materialov s specifi~nimi mehanskimi in fizikalnimi lastnostmi, ki odpirajo nove mo`nosti uporabe v industriji. Metalurgija prahov omogo~a uporabo prahov s kovinsko osnovo z dispergiranimi stabilnimi delci, ki jih dobimo pri mehanskem legiranju in vro~i konsolidaciji z valjanjem. Nove zlitine Fe-Al, disperzijsko utrjene z oksidi (ODS), so bile preizku{ene pri razli~ni, eno-ali ve~stopenjski obdelavi pri razli~nih temperaturah. Rezultati ka`ejo, da ima termomehanska obdelava novih ODS zlitin mo~an vpliv, ki se vidi v spremembah mikrostrukture. Analiza je bila izvedena s pomo~jo razli~nih analitskih metod, kot so: svetlobna mikroskopija, vrsti~na elektronska mikroskopija in rentgenska difrakcijska analiza.

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“…The typical creep strength of the ferritic ODS alloys is estimated, in the available literature, to be 60 (40) MPa for coarse-grained structures and 20 (6) MPa for fine-grained structures at 1000 (1100)°C 9 . New ODS ferritic steels are currently in development at Oak Ridge National Laboratories [10][11][12][13] . Sufficient amounts of Al and/or Cr in the ODS alloys are crucial for their oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

Investigation on new creep- and oxidation-resistant materials

Khalaj¹,

Mašek²,

Jirková³

2015

Mater. Tehnol.

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The specific mechanical property and structure of a material can be achieved by combining various types of materials and technologies. The main aim of this research is to develop new creep-and oxidation-resistant materials (ODS) (new ODS Fe-Al based alloys and ODS composites) applicable at high temperatures of up to about 1100°C. The new ODS composites consist of a ferritic Fe-Al matrix strengthened with about volume fractions 2 % to 30 % of Al2O3 particles. In order to find the optimum material structure, different oxide amounts were added to three different containers. Also, to find the influence of the temperature on the obtained structures, three processing temperatures of (26, 750 and 1150)°C were used with the specific deformation profile. An analysis of the structures was performed using different analytical methods such as light microscopy, scanning electron microscopy and X-ray diffraction analysis. Keywords: ODS steel, alloys, composite, creep, Fe-Al Posebne mehanske lastnosti in strukturo materiala je mogo~e dose~i s kombinacijo razli~nih vrst materialov in tehnologij. Glavni namen tega~lanka je razviti nov material, odporen proti lezenju in oksidaciji (ODS), tj. novo ODS-zlitino na osnovi Fe-Al in ODS-kompozite, uporabne pri visokih temperaturah do 1100°C. Novi ODS-kompozit je sestavljen iz feritne Fe-Al-osnove, oja~ane z okrog volumenskim dele`em od 2 % do 30 % delcev Al2O3. Da bi dobili optimalno strukturo materiala, je bil v tri vsebnike prime{an razli~en dele`oksida. Za ugotovitev vpliva temperature na dobljeno strukturo so bile uporabljene tri temperature izdelave (26, 750 in 1150)°C s posebnim profilom deformacije. Analiza strukture je bila izvr{ena z razli~nimi metodami, kot so svetlobna mikroskopija, vrsti~na elektronska mikroskopija in rentgenska difrakcija.

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Morphology, structure, and chemistry of nanoclusters in a mechanically alloyed nanostructured ferritic steel

Cited by 86 publications

References 53 publications

Temperature-dependent elastic anisotropy and mesoscale deformation in a nanostructured ferritic alloy

Temperature-dependent elastic anisotropy and mesoscale deformation in a nanostructured ferritic alloy

Behaviour of new ODS alloys under single and multiple deformation

Investigation on new creep- and oxidation-resistant materials

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