scholarly journals Different Radiation Tolerances of Ultrafine-Grained Zirconia–Magnesia Composite Ceramics with Different Grain Sizes

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2649
Author(s):  
Wenjing Qin ◽  
Mengqing Hong ◽  
Yongqiang Wang ◽  
Jun Tang ◽  
Guangxu Cai ◽  
...  
Keyword(s):  
Grain Size ◽  
Ion Irradiation ◽  
Composite Ceramic ◽  
Heavy Ion ◽  
Composite Ceramics ◽  
Displacement Damage ◽  
Inert Matrix ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Nuclear Systems

Developing high-radiation-tolerant inert matrix fuel (IMF) with a long lifetime is important for advanced fission nuclear systems. In this work, we combined zirconia (ZrO2) with magnesia (MgO) to form ultrafine-grained ZrO2–MgO composite ceramics. On the one hand, the formation of phase interfaces can stabilize the structure of ZrO2 as well as inhibiting excessive coarsening of grains. On the other hand, the grain refinement of the composite ceramics can increase the defect sinks. Two kinds of composite ceramics with different grain sizes were prepared by spark plasma sintering (SPS), and their radiation damage behaviors were evaluated by helium (He) and xenon (Xe) ion irradiation. It was found that these dual-phase composite ceramics had better radiation tolerance than the pure yttria-stabilized ZrO2 (YSZ) and MgO. Regarding He+ ion irradiation with low displacement damage, the ZrO2–MgO composite ceramic with smaller grain size had a better ability to manage He bubbles than the composite ceramic with larger grain size. However, the ZrO2–MgO composite ceramic with a larger grain size could withstand higher displacement damage in the phase transformation under heavy ion irradiation. Therefore, the balance in managing He bubbles and phase stability should be considered in choosing suitable grain sizes.

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

Behaviour of Nanocrystalline Silicon Carbide Under Low Energy Heavy Ion Irradiation

2009 ◽  
Vol 1215 ◽  
Author(s):  
Dominique Gosset ◽  
Laurence Luneville ◽  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Auregane Audren ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Grain Size ◽  
Ion Irradiation ◽  
Healing Process ◽  
Grazing Incidence ◽  
Nanocrystalline Silicon ◽  
Heavy Ion ◽  
Before And After ◽  
Gen Iv ◽  
Nanocrystalline Silicon Carbide

AbstractSilicon carbide is one of the most studied materials for core components of the next generation of nuclear plants (Gen IV). In order to overcome its brittle properties, materials with nanometric grain size are considered. In spite of the growing interest for nano-structured materials, only few experiments deal with their behaviour under irradiation. To assess and predict their evolution under working conditions, it is important to characterize their microstructure and structure. To this purpose, we have studied microcrystalline and nanocrystalline samples before and after irradiation at room temperature with 4 MeV Au ions. In fact, it is well established that such irradiation conditions lead to amorphisation of the material, which can be restored after annealing at high temperature. We have performed isochronal annealings of both materials to point out the characteristics of the healing process and eventual differences related to the initial microstructure of the samples. To this purpose Grazing Incidence X-Ray Diffraction has been performed to determine the microstructure and structure parameters. We observe the amorphisation of both samples at similar doses but different annealing kinetics are observed. The amorphous nanocrystalline sample recovers its initial crystalline state at higher temperature than the microcrystalline one. This effect is clearly related to the initial microstructures of the materials. Therefore, the grain size appears as a key parameter for the structural stability and mechanical properties of this ceramic material under irradiation.

Study of Machining-Induced Microstructure Variations of Nanostructured/Ultrafine-Grained Copper Using XRD

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Yong Huang ◽  
Mason Morehead
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Dislocation Density ◽  
Equal Channel Angular Extrusion ◽  
Outer Radius ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Area And Volume

Various methods for the production of bulk nanostructured (NS)/ultrafine-grained (UFG) materials have been developed, including equal channel angular extrusion (ECAE), a form of severe plastic deformation. Using an ECAE NS/UFG copper bar as an example, this study has investigated machining-induced workpiece microstructure variation using X-ray diffraction. It has been found that (1) under gentle cutting conditions, there was a 10% increase in the median grain size compared with unmachined ECAE NS/UFG copper bars. Increases in the arithmetic-, area-, and volume-weighted grain sizes were found to be 10%, 8%, and 8%, respectively, and (2) an average 27% drop in the dislocation density was observed between the machined and unmachined ECAE copper bars. The dislocation density was shown to have the most reduction (−39%) at the outer radius of the machined ECAE bar where more heat and/or higher pressure were experienced.

Zirconia Inert Matrix for Plutonium Utilisation and Minor Actinides Disposition in Thermal Reactors

2006 ◽  
Vol 45 ◽  
pp. 1907-1914
Author(s):  
Claude Degueldre
Keyword(s):  
Solid Solution ◽  
Ion Irradiation ◽  
Near Field ◽  
Fission Products ◽  
Heavy Ion ◽  
Minor Actinide ◽  
Minor Actinides ◽  
Spent Fuel ◽  
Geological Disposal ◽  
Inert Matrix

The toxicity of the UO2 spent fuel is dominated by plutonium and minor actinides (MA): Np, Am and Cm, after decay of the short live fission products. Zirconia ceramics containing Pu and MA in the form of an Inert Matrix Fuel (IMF) could be used to burn these actinides in Light Water Reactors. Optimisation of the fuel designs dictated by properties such as thermal, mechanical, chemical and physical must be performed with attention for their behaviour under irradiation. Zirconia must be stabilised by yttria to form a solid solution such as AnzYyPuxZr1-yO2-y where minor actinide oxides are also soluble. Burnable poison may be added if necessary such as Gd, Ho, Er, Eu or Np, Am them-self. These cubic solid solutions are stable under heavy ion irradiation. The retention of fission products in zirconia, under similar thermodynamic conditions, is a priori stronger, compared to UO2, the lattice parameter being larger for UO2 than for (Y,Zr)O2-x. (Er,Y,Pu,Zr)O2-x in which Pu contains 5% Am was successfully irradiated in the Proteus reactor at PSI, in the HFR facility, Petten as well as in the Halden Reactor. These irradiations make the Swiss scientists confident to irradiate such IMF in a commercial reactor that would allow later a commercial deployment of such a fuel for Pu and MA utilisation in a last cycle. The fuel forms namely pellet of solid solution, cercer or cermet fuel are discussed considering the once through strategy. For this strategy, low solubility of the inert matrix is required for geological disposal. As spent fuels these IMF’s are demanding materials from the solubility point of view, this parameter was studied in detail for a range of solutions corresponding to groundwater under near field conditions. Under these conditions the IMF solubility is 106 times smaller than glass, which makes the zirconia material very attractive for deep geological disposal. The desired objective would be to use IMF to produce energy in reactors, opting for an economical and ecological solution.

Dislocation and Diffusion Deformation Mechanisms of Ultrafine Grained Materials

2009 ◽  
Vol 633-634 ◽  
pp. 121-128 ◽  
Author(s):  
Eduard Kozlov ◽  
Nina Koneva ◽  
N.A. Popova
Keyword(s):  
Grain Size ◽  
Deformation Mechanisms ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Diffusion Mechanisms ◽  
Ultrafine Grained Materials ◽  
And Diffusion

Deformation mechanisms of polycrystals as a function of the grain size in the 1nm…1cm interval are studied in this paper. The critical grain sizes are identified. Activity of dislocation and diffusion mechanisms is analyzed. The distribution of deformation in grains with different sizes within the same polycrystal is considered.

Measurement of WC Grain Size in Ultrafine Grained WC-Co Cemented Carbides

2013 ◽  
Vol 278-280 ◽  
pp. 460-463 ◽  
Author(s):  
Yi Gao Yuan ◽  
Xiao Xiao Zhang ◽  
Jian Jun Ding ◽  
Jun Ruan
Keyword(s):  
Grain Size ◽  
Diffraction Method ◽  
Cemented Carbides ◽  
Polished Surface ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Measurement Results ◽  
Backscattered Electron ◽  
Imagej Software

Based on the backscattered electron (BSE) images and IMAGEJ image analysis software, the average grain size of WC in ultrafine grained WC-Co cemented carbides was measured. The result shows that BSE images of the polished surface not be etched are suitable for quantitative evaluating the grain size of WC in the ultrafine grained hardmetals. Both linear intercept method and equivalent circle diameter method can be used to accurately measure the grain sizes of WC in ultrafine grained hadmetals by using IMAGEJ software. Measurement results of WC grain sizes coincide with the conclusion of X-ray diffraction method

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