Effect of bulk oxygen on 14YWT nanostructured ferritic alloys

Cunningham, N.J.; Wu, Yuan; Etienne, Auriane; Haney, E; Odette, G.R.; Stergar, Erich; Hoelzer, David T.; Kim, Y.D.; Wirth, Brian D.; Maloy, S.A.

doi:10.1016/j.jnucmat.2013.09.013

Cited by 30 publications

(21 citation statements)

References 7 publications

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“…Evidently, in the kinetic model the driving force for TiO 2 precipitation is not sufficient to overcome the barrier to nucleation over the range of interfacial energy values investigated, even though this phase is thermodynamically stable in this regime. It is notable that while TiO 2 is observed in MA957 following hot extrusion, a much larger fraction of this element precipitates during long term thermal aging at 1000°C, resulting in a removal of a large excess of Ti from the matrix that is left after the Y-bearing nanoparticles initially form [23]. The suppression of the TiO 2 nucleation observed in the kinetic model is qualitatively consistent with this observation.…”

Section: Calculation Of the Initial Particle Size Distributionsupporting

confidence: 72%

“…6 [23]. There are some important differences between the purely thermodynamic predictions and the results of the kinetic calculations in Fig.…”

Section: Calculation Of the Initial Particle Size Distributionmentioning

confidence: 84%

“…Furthermore, it is known that O in excess of the amount added in the form of the Y 2 O 3 powder is needed to form fine complex oxide nanoprecipitates [14,26]. Cunningham et al recently demonstrated that improved impurity control during powder milling reduces the amount of excess O [23], and that nano-oxide formation is inhibited for very low O contents. The O potentials in equilibrium with known Fe and Cr oxides correspond to O partial pressures (hereafter denoted P O 2 ) in the range of 10 À23 -10 À15 atm and O solubility values in the range of 10 À4 -10 À2 at.% over the temperature range of interest here, based on the calculated phase diagrams [27].…”

Section: Thermodynamic Modelmentioning

confidence: 99%

“…Indeed, non-equilibrium O concentrations in excess of that added by Y 2 O 3 are needed to produce optimal Y-Ti nano-oxides [23]. As the concentration of O within the alloy is difficult to control, and likely fluctuates over the course of alloy processing, we use the O chemical potential within the alloy as an adjustable parameter in the model.…”

Section: Introductionmentioning

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: Calculation Of the Initial Particle Size Distributionsupporting

confidence: 72%

“…6 [23]. There are some important differences between the purely thermodynamic predictions and the results of the kinetic calculations in Fig.…”

Section: Calculation Of the Initial Particle Size Distributionmentioning

confidence: 84%

Section: Thermodynamic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys

et al. 2015

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“…NFAs are usually processed by first ball milling metal 14Cr-Fe-Ti-W and yttria (Y 2 O 3 ) powders, thereby forcing the practically insoluble Y and O into solution [19][20][21] . The mechanically alloyed powders are typically then canned, degassed and consolidated by hot isostatic pressing or hot extrusion.…”

Section: Introductionmentioning

confidence: 99%