Modelling precipitation in zirconium niobium alloys

Robson, James

doi:10.1016/j.jnucmat.2008.03.016

Cited by 20 publications

(8 citation statements)

References 28 publications

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“…mobility) data to predict the essential processes that occur during precipitate evolution, namely nucleation, growth and coarsening. It has also been widely applied to a number of alloy systems (including stainless steel 316) with the advantage of naturally predicting the evolution of precipitates from nucleation to growth and coarsening without imposed constraints [16,17,[19][20][21][22]. The KWN model requires knowledge of the thermodynamic properties of the precipitate and matrix phase (to calculate interfacial compositions) and the diffusion coefficient of the rate controlling element(s).…”

Section: Several Investigations Have Reported the Precipitation Behavmentioning

confidence: 99%

Numerical simulation of grain boundary carbides evolution in 316H stainless steel

Xiong

Robson

Chang

et al. 2018

Journal of Nuclear Materials

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In the present work, a numerical model based on the coupling of Kampmann and Wagner Numerical (KWN) framework and thermodynamic software ThermoCalc has been developed to predict grain boundary precipitate evolution in 316H stainless steel during thermal aging. The model is calibrated and validated against precipitate size distributions obtained by accelerated isothermal heat treatment and analysed using scanning electron microscopy (SEM). Elemental distribution was also investigated using electron microprobe analysis (EPMA). The predicted average particle size, particle size distribution and precipitate number density predicted by the model were found to be in good agreement with the experimental results. The model was then applied to predict the particle size distribution after several years exposure at service temperature. It is demonstrated that these predictions are consistent with measurements from a service-exposed part. The sensitivity of the precipitate size distribution to temperature is emphasised, and it is demonstrated that the model has potential as a useful tool for predicting evolution of the precipitate size distribution during service, providing reliable thermal data are available for the whole service life.

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Section: Several Investigations Have Reported the Precipitation Behavmentioning

confidence: 99%

Numerical simulation of grain boundary carbides evolution in 316H stainless steel

Xiong

Robson

Chang

et al. 2018

Journal of Nuclear Materials

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“…The interfacial energy for the Zr matrix and b-Nb precipitates was obtained from the literature to be 0:19 J/m 2 , [62,63] which is assumed for the newly formed interface due to particle sharing in HANA-4 as well. Thus, the stress required to shear the b-Nb precipitates in HANA-4 was calculated to be 308 MPa.…”

Section: Transition From Regime II To Regime Iiimentioning

confidence: 99%

Coble, Orowan Strengthening, and Dislocation Climb Mechanisms in a Nb-Modified Zircaloy Cladding

Kombaiah

Murty

2015

Metall Mater Trans A

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BOOPATHY KOMBAIAH and KORUKONDA LINGA MURTYBiaxial creep tests on HANA-4 tubes, Nb-added Zircaloy-4 were conducted using internal pressurization of closed-end tubes to investigate the rate-controlling mechanisms over a range of hoop stresses, 8:38 Â 10 À5 E À 2:87 Â 10 À3 E, at three different temperatures 673 K, 723 K, and 773 K (400°C, 450°C, and 500°C). The mechanistic creep parameters such as stress exponent (n) and activation energy (Q C ) were then determined from steady-state creep rates. Based on the variance in stress exponent with respect to the applied stress, three regimes have been identified: a stress exponent close to 1 at low stresses that increased to 3 at the intermediate stresses, which became 4.5 at high stresses. An activation energy value of 226 kJ/mol was evaluated for the n = 3 and n = 4.5 regimes, which lies close to the activation energy for self-diffusion (Q L ) in a-Zr alloys. Further, TEM analyses of crept microstructures and comparison of experimental results with standard models were undertaken to find out the rate-controlling mechanisms. Coble creep, climbing of dislocations to bypass b-Nb precipitates, and dynamic recovery by edge dislocation climb are proposed as the rate-controlling mechanisms in the n = 1, n = 3, and n = 4.5 regimes of HANA-4, respectively.

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“…Second, the nucleation and growth process of b-Zr SPPs is interfered with by the existence of b-Nb SPPs. In fact, Robson [11] proposed that the retained b-Zr has an apparent effect on the kinetics of a subsequent b-Nb evolution. The incubation times for the nucleation of b-Zr SPPs can therefore be affected by the prior heat-treatment process.…”

Section: Resultsmentioning

confidence: 99%