Transmission electron microscopy characterization of the nanofeatures in nanostructured ferritic alloy MA957

Wu, Yuan; Haney, E; Cunningham, N.J.; Odette, G.R.

doi:10.1016/j.actamat.2012.03.012

Cited by 109 publications

(59 citation statements)

References 33 publications

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“…Over the range of P O 2 for which Fe or Cr oxides are stable, the predicted phases are Y 2 O 3 , TiO 2 , Y 2 Ti 2 O 7 , and Y 2 TiO 5 , depending on the Y and Ti alloy composition. Most NFAs occupy the Ti-rich composition range for which the predicted stable phases are TiO 2 and Y 2 Ti 2 O 7 , in good qualitative agreement with many experimental observations [9,10,11,12,50]. The phase stability behavior is insensitive to the P O 2 above the threshold of P O 2 ¼ 10 À28 atm necessary to form Ti containing oxides.…”

Section: Predictions Of Phases and Volume Fraction At Equilibriumsupporting

confidence: 81%

“…Most high-resolution TEM studies show that the nano-oxides are consistent with Y 2 Ti 2 O 7 [8][9][10]. Combined small angle neutron and X-ray scattering [10][11][12] and X-ray diffraction measurements [13,14] are also broadly consistent with this conclusion.…”

Section: Introductionsupporting

confidence: 79%

“…These constraints are equivalent to assuming that the system is closed with respect to the metallic constituents, but open with respect to O. The assumption of openness is based on ubiquitous observations that the initially dissolved O in NFA significantly exceeds the nominal solubility in equilibrium with the oxides of Fe, Ti and Cr [4][5][6][7][8][9]. The precise value of this O chemical potential is unknown.…”

Section: Thermodynamic Modelmentioning

confidence: 99%

“…The kinetic model was first used to simulate the nucleation and growth of the oxide nanoprecipitates from the solid solution, in order to obtain an initial number density and size distribution consistent with SANS measurements for as-consolidated MA957 [9][10][11]. The base MA957 material exhibits a mean nanoprecipitate radius of 1.35 nm and a density of 9.0 Â 10 23 m À3 after consolidation at 1338 K [10].…”

Section: Calculation Of the Initial Particle Size Distributionmentioning

confidence: 99%

“…The model was fit using the experimental data from the alloy MA957 [9][10][11]14,48]. This alloy was chosen because of the availability of data on nanoparticle size and number density for this extensively studied material under multiple aging conditions, thus avoiding complexities associated with fitting to data from alloys with different compositions and processing histories.…”

Section: Physical Quantities Used As Adjustable Parametersmentioning

confidence: 99%

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Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

et al. 2015

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The mechanical properties and radiation tolerance of nanostructured ferritic alloys rely on a dense population of nanometer-scale Y-Ti oxides. The stability of these nano-oxides during extended service is critical in high temperature applications. Here, a model framework is developed for the thermodynamics and kinetics of Y-Ti oxide nucleation, growth and coarsening. The model, which is based upon available thermodynamic and kinetic data as well as key density functional theory calculations, shows that nano-oxide nucleation and growth are highly driven and that pipe diffusion is the dominant mode of their coarsening, in agreement with previous analyses of experimental high temperature data. The model predicts that the nano-oxides are thermally stable for 80 or more years below 1175 K. This analysis also provides insights into the effect of O and Ti on nanooxide sizes, and on optimization of alloy microstructure.

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Section: Predictions Of Phases and Volume Fraction At Equilibriumsupporting

confidence: 81%

Section: Introductionsupporting

confidence: 79%

Section: Thermodynamic Modelmentioning

confidence: 99%

Section: Calculation Of the Initial Particle Size Distributionmentioning

confidence: 99%

Section: Physical Quantities Used As Adjustable Parametersmentioning

confidence: 99%

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Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

et al. 2015

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Characterization of M-O bonds in Y₂Ti₂O₇and Y₂TiO₅with EELS

Jegadeesan

Amirthapandian

Kaur

et al. 2014

Phys. Status Solidi B

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The nature of metal-oxygen (M-O) bonds in Y 2 Ti 2 O 7 and Y 2 TiO 5 is studied using electron energy loss spectroscopy (EELS) and density functional theory (DFT) calculations. The samples are synthesized by the conventional solid state reaction route and characterized with EELS. For both the oxides (Y 2 Ti 2 O 7 and Y 2 TiO 5 ), the crystal field splitting in Ti 3d orbital is manifested in the pre-edge features of the O K edge, which is an outcome of the covalent mixing of the metal 3d and oxygen 2p orbitals. Further, the intensities of pre-edge features are weak in Y 2 TiO 5 which implies that the metal-oxygen (M-O) bonds are highly ionic in nature. The calculated electronic charge densities confirm our experimental observation. ß 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2 Experimental and computational methods 2.1 Synthesis and characterization The powder samples of Y 2 Ti 2 O 7 and Y 2 TiO 5 are synthesized by the conventional solid state reaction route from the precursor materials Y 2 O 3 and TiO 2 . The stoichiometric mixture of the precursor materials for Y 2 Ti 2 O 7 was calcined at 1,250 8C in air for 48 h [8] and the mixture for Y 2 TiO 5 was calcined at 1,500 8C in air for 24 h [9]. The phase formation is confirmed by the powder X-ray diffraction (XRD) measurements using STOE X-ray diffractometer with Cu-K a radiation.

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Nanostructured Steels

Rementería

Capdevila

Caballero

2020

High-Performance Ferrous Alloys

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Transmission electron microscopy characterization of the nanofeatures in nanostructured ferritic alloy MA957

Cited by 109 publications

References 33 publications

Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Characterization of M-O bonds in Y₂Ti₂O₇and Y₂TiO₅with EELS

Nanostructured Steels

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Transmission electron microscopy characterization of the nanofeatures in nanostructured ferritic alloy MA957

Cited by 109 publications

References 33 publications

Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

Characterization of M-O bonds in Y2Ti2O7and Y2TiO5with EELS

Nanostructured Steels

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Product

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Characterization of M-O bonds in Y₂Ti₂O₇and Y₂TiO₅with EELS