Ternary Zr–Nb–Fe(O) system: phase diagram at 853 K and corrosion behaviour in the domain Nb&lt;0.8%

Barbéris, Pierre; Charquet, D.; Rebeyrolle, V.

doi:10.1016/j.jnucmat.2004.01.007

Cited by 77 publications

(34 citation statements)

References 24 publications

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“…At 900°C has a wide range of compositions. Comparing the obtained values to our previous work [1][2][3][4] for alloys with variable compositions and considering that those values do not contradict values found in literature for precipitates of this phase in different Zr alloys [5,7,[18][19][20][21], we could say that this phase would extend over the following composition range: 34 < at.% Zr < 40, 5 < at.% Nb < 36, 30 < at.% Fe < 55. Then, the lower existence range of this phase respecting the Fe content would be around 30 at.% Fe, 36 at.% Nb and 34 at.% Zr and the upper existence range respecting the Fe content would be around 55 at.% Fe, 5 at.% Nb and 40 at.% Zr.…”

Section: K 2 Phase (Zr(nbfe) 2 )supporting

confidence: 77%

“…Comparing the composition values obtained with previous works results and considering that there are no contradiction with values obtained in the literature for precipitates of this phase in different Zr alloys [5,[19][20][21]32], we can say that it would extend over the following range of composition: 54 < at.% Zr < 64.5, 0.5 < at.% Nb < 16, 30 < at.% Fe < 35.…”

Section: K 1 Phase -(Zrnb) 2 Fesupporting

confidence: 73%

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Some new experimental results on the Zr–Nb–Fe system

Ramos

Saragovi

Granovsky

2007

Journal of Nuclear Materials

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Section: K 2 Phase (Zr(nbfe) 2 )supporting

confidence: 77%

Section: K 1 Phase -(Zrnb) 2 Fesupporting

confidence: 73%

Some new experimental results on the Zr–Nb–Fe system

Ramos

Saragovi

Granovsky

2007

Journal of Nuclear Materials

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“…Table 1). Among the literature many reports exist of both the cubic C15 [13][14][15][16][17][18] and the two hexagonal C14 and C36 [13,[16][17][18][19][20][21][22][23] Laves phases. Due to the nominal composition of commercial alloys, these SPPs have mostly been identified as Zr(Cr,Fe) 2 and Zr(Nb,Fe) 2 , however, they are also known to form with Mo and V additions [13,[24][25][26][27].…”

Section: Crystallography Of Intermetallic Phasesmentioning

confidence: 99%

“…Zr is known to of Cr additions, while in Cr-containing alloys, Zr(Cr,Fe) 2 Laves phases become the dominant SPPs [29]. In the presence of Nb, hexagonal Zr(Nb,Fe) 2 Laves phases and cubic (Zr,Nb) 2 Fe phases have been reported [13].…”

Section: Phasementioning

confidence: 99%

Hydrogen solubility in zirconium intermetallic second phase particles

Burr

Murphy

Lumley

et al. 2013

Journal of Nuclear Materials

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The enthalpies of solution of H in Zr binary intermetallic compounds formed with Cu, Cr, Fe, Mo, Ni, Nb, Sn and V were calculated by means of density functional theory simulations and compared to that of H in α-Zr. It is predicted that all Zr-rich phases (formed with Cu, Fe, Ni and Sn), and those phases formed with Nb and V, offer lower energy, more stable sites for H than α-Zr. Conversely, Mo and Cr containing phases do not provide preferential solution sites for H. In all cases the most stable site for H are those that offer the highest coordination fraction of Zr atoms. Often these are four Zr tetrahedra but not always. Implications with respect to H-trapping properties of commonly observed ternary phases such as Zr(Cr,Fe) 2 , Zr 2 (Fe,Ni) and Zr(Nb,Fe) 2 are also discussed.

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“…An alloy containing 0.4%wt in niobium (Zr0.4%NbO) has been used, in order to compare its oxidation behaviour to ZrNbO one. This alloy does not contain β-Nb precipitates but contains Zr(Nb, Fe) 2 phases [23]. The oxidation curves giving the oxide thickness X versus time, obtained for the two alloys at 520°C under 13 hPa in hydrogen and 67 hPa in water vapour are represented on Fig.…”

Section: Resultsmentioning

confidence: 99%

Oxidation kinetics of ZrNbO in steam: Differences between the pre- and post-transition stages

Tupin

Pijolat

Valdivieso

et al. 2005

Journal of Nuclear Materials

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Zirconium based alloys (and particularly Zircaloy-4) are widely used as cladding material of fuel rods in water-cooled nuclear reactors. However, advanced alloys are now used for longer operation time in more severe conditions. One of these new alloys is a ZrNbO, which contains 1% of Nb as alloying element (instead of Sn in the case of Zircaloy-4).This ZrNbO alloy, like many zirconium alloys, undergoes a kinetic transition, which is a sharp increase in the oxidation rate when the oxide thickness exceeds a critical value. In the pre-transition stage, the kinetic oxidation curves are approximately parabolic (which is generally interpreted by a diffusion controlling step), and tend towards a quasi-linear behaviour after the transition. Recent studies have shown that the oxygen pressure has an accelerating effect on the oxidation rate of ZrNbO; a platinum layer deposited on the oxide surface has the same effect, both in oxygen and in water vapour. Thus it has been suggested that the oxidation in the pre-transition stage could be described by a mixed reaction-diffusion kinetics. Due to the lack of consistent data on the effect of water vapour on the oxidation rate of ZrNbO before and after the transition, and to confirm (or not) these interpretations, we have studied the oxidation of ZrNbO by isothermal thermogravimetry at 550°C, under controlled partial pressures of water vapour (13 to 80 hPa) and hydrogen (10 hPa). The aim is to verify if the oxidation proceeds in a steady state and if there is a rate-limiting step in one (or both) stages, and to clearly evidence the differences between the pre-and post transition stages from the kinetic point of view.TG-DSC experiments have shown that the system is in a steady state from the beginning of the oxidation, in the pre-and post-transition stages. Then, the existence of a ratelimiting step was verified using an experimental method based on temperature or pressure jumps: it has been concluded that this assumption is valid in both stages, which is not compatible with the assumption of a mixed reaction-diffusion controlled rate). Moreover, it comes out that the kinetic behaviour is different before and after the transition: the influence of temperature jumps is greater in pre-transition, whereas the effect of water vapour partial pressure is more pronounced in post-transition (nevertheless, an accelerating effect is also observed before the transition). No influence of hydrogen partial pressure has been observed. Besides, the higher the Nb content in the alloy, the higher the oxidation rate (in pre-transition). A mechanism has been proposed to account for the results obtained in pretransition, involving the diffusion of adsorbed species in the porous part of the oxide layer as rate-determining step.Keywords: ZrNbO ; oxidation ; kinetics ; water vapour ; steady state ; rate-limiting step. 1 IntroductionDespite numerous works dedicated to the oxidation kinetics of zirconium alloys by pressurized water, water vapour or oxygen, the mechanisms and the rate-limiting steps...

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Ternary Zr–Nb–Fe(O) system: phase diagram at 853 K and corrosion behaviour in the domain Nb<0.8%

Cited by 77 publications

References 24 publications

Some new experimental results on the Zr–Nb–Fe system

Some new experimental results on the Zr–Nb–Fe system

Hydrogen solubility in zirconium intermetallic second phase particles

Oxidation kinetics of ZrNbO in steam: Differences between the pre- and post-transition stages

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