Stoichiometry effect on the irradiation response in the microstructure of zirconium carbides

Yang, Young Hwan; Lo, Wei-Yang; Dickerson, Clayton; Allen, Todd R.

doi:10.1016/j.jnucmat.2014.07.071

Cited by 28 publications

(10 citation statements)

References 12 publications

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“…2 Similarly, variable carbon stoichiometry is exhibited by other TMCs, such as TiC x , [3][4][5] HfC x , 6,7 VC x , 8 NbC x , 3,9 TaC x , 10,11 and WC x . 12 Carbon stoichiometry affects the sinterability, [13][14][15] mechanical properties, 16,17 electrical properties, 18 and radiation resistance 19 of ZrC x ceramics. Short-and long-range ordering of carbon vacancies in nonstoichiometric carbides have both been studied theoretically.…”

Section: Introductionmentioning

confidence: 99%

Carbon vacancy ordering in zirconium carbide powder

et al. 2019

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Ordered carbon vacancies were detected in zirconium carbide (ZrCx) powders that were synthesized by direct reaction. Zirconium hydride (ZrH2) and carbon black were used as starting powders with the molar ratio of ZrH2:C = 1:0.6. Powders were reacted at 1300°C or 2000°C. The major phase detected by x‐ray diffraction (XRD) was ZrCx. No excess carbon was observed by transmission electron microscopy (TEM) in powders synthesized at either temperature. Ordering of the carbon vacancies was identified by neutron powder diffraction (NPD) and further supported by selected area electron diffraction (SAED). The vacancies in carbon‐deficient ZrCx exhibited diamond cubic symmetry with a supercell that consisted of eight (2 × 2 × 2) ZrCx unit cells with the rock‐salt structure. Rietveld refinement of the neutron diffraction patterns revealed that the synthesis temperature did not have a significant effect on the degree of vacancy ordering in ZrCx powders. Direct synthesis of ZrC0.6 resulted in the partial ordering of carbon vacancies without the need for extended isothermal annealing as reported in previous experimental studies.

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Section: Introductionmentioning

confidence: 99%

Carbon vacancy ordering in zirconium carbide powder

et al. 2019

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“…[11]. The Z contrast spherical aberration corrected STEM image of proton irradiated ZrC further confirms that those loops are interstitial type dislocation loops [20]. This indicates that the dislocation loops might be surrounded by C vacancies that have a much lower mobility as compared with C interstitials, however, there is no direct experimental evidence to confirm this yet.…”

Section: Methodsmentioning

confidence: 93%

Using a spherical crystallite model with vacancies to relate local atomic structure to irradiation defects in ZrC and ZrN

Olive

Ganegoda

Allen

et al. 2016

Journal of Nuclear Materials

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“…Studies have indicated that the properties of ZrC vary with its stoichiometry (C/Zr atomic percentage ratio) [9]. For example Yang et al [25] indicated that the C/Zr ratio had a notable effect on the irradiation response of zone-refined ultra-high pure ZrC. They noted that the sub-stoichiometric ZrC samples (C/Zr<1) had an improved irradiation resistant microstructure compered to hyper-stoichiometric ZrC samples (C/Zr>1).…”

Section: Zrcmentioning

confidence: 99%

Optimisation of the synthesis of ZrC coatings in a radio frequency induction-heating chemical vapour deposition system using response surface methodology

et al. 2017

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A chemical vapour deposition process using radio frequency induction heating operating at atmospheric pressure was developed for the deposition of ZrC coatings. The precursors utilised in this process were zirconium tetrachloride and methane as zirconium and carbon sources respectively, in an excess of hydrogen. Additionally, a stream of argon was used to, first, remove oxygen from the reactor and then to sweep the vapourised ZrCl 4 at 300 °C to the reaction chamber. The ZrC coatings were deposited on graphite substrates at substrate temperatures in the range of 1200 °C-1600 °C. The molar ratio of CH 4 /ZrCl 4 was varied from 6.04 to 24.44. Before the start of the deposition process, thermodynamic feasibility analysis for the growth of ZrC at atmospheric pressure was also carried out. Response surface methodology was applied to optimise the process parameters for the deposition of ZrC coatings. A central composite design was used to investigate the effects of temperature and molar ratio of CH 4 /ZrCl 4 on the growth rate, atomic ratio of C/Zr and crystallite size of ZrC 2 coatings. Quadratic statistical models for growth rate and crystallite size were established. The atomic ratio of C/Zr followed a linear trend. It was found that an increase in substrate temperature and CH 4 /ZrCl 4 ratio resulted in increased growth rate of ZrC coatings. The carbon content (and concomitantly the atomic ratio of C/Zr) in the deposited coatings increased with temperature and molar ratio of CH 4 /ZrCl 4. The substrate temperature of 1353.3°C and the CH 4 /ZrCl 4 molar ratio of 10.41 was determined as the optimal condition for growing near-stoichiometry ZrC coatings. The values were 1.03, 6.05 µm/h and 29.8 nm for C/Zr atomic percentage ratio, growth rate and average crystallite size respectively.

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Stoichiometry effect on the irradiation response in the microstructure of zirconium carbides

Abstract: 2016-12-23T18:47:23

Cited by 28 publications

References 12 publications

Carbon vacancy ordering in zirconium carbide powder

Carbon vacancy ordering in zirconium carbide powder

Using a spherical crystallite model with vacancies to relate local atomic structure to irradiation defects in ZrC and ZrN

Optimisation of the synthesis of ZrC coatings in a radio frequency induction-heating chemical vapour deposition system using response surface methodology

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