Yeonju Oh
Seoul National University
Ternary numeral systemVickers hardness testCeramicMockupSolid solutionNanocrystalline materialRecrystallization (metallurgy)DislocationHeat fluxComposite materialCastingFlexural strengthEutectic systemTensile testingThin filmMetallurgyGrain sizeMaterials scienceFluxShear stressSputteringSpark plasma sinteringLaves phaseSinteringLanthanum oxideDiffusion barrierOxideAlloyHot isostatic pressingTantalum carbideCompressive strengthThermal diffusivityFracture (geology)Elastic modulusPhase (matter)Grain boundaryCarbonTantalumCarbideTungstenMolybdenumDuctilityTernary operationElectrical resistivity and conductivityAnnealing (metallurgy)Lamellar structureStrengthening mechanisms of materialsPlasticityGrain boundary strengtheningBrazingMicrostructureThermal conductivity
8Publications
4H-index
27Citations
Publications 10
Newest
#1Yeonju Oh (SNU: Seoul National University)H-Index: 4
#2Won-Seok Ko (UOU: University of Ulsan)H-Index: 15
Last. Heung Nam Han (SNU: Seoul National University)H-Index: 41
view all 6 authors...
Abstract null null Tungsten as a material exhibits broad and increasingly important applications; however, the characterization of its ductile-to-brittle transition (BDT) is currently limited to large-scale scenarios and destructive testing. In this study, we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure tungsten. In order to predict the failure mode at various temperature ranges, the practical fracture analysi...
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#1Abbas Sabahi Namini (UMA: University of Mohaghegh Ardabili)H-Index: 35
#2Seyed Ali Delbari (SNU: Seoul National University)H-Index: 24
Last. Mohammadreza Shokouhimehr (SNU: Seoul National University)H-Index: 51
view all 10 authors...
Abstract The present investigation was carried out to illustrate the effect of TiCN on the microstructure development of spark plasma sintered fully dense ZrB2-based ceramics. The microstructural observations, X-ray diffraction patterns, and field emission-electron probe microanalysis revealed the presence of the (Zr,Ti)B2 and ZrCN phases in the final microstructures of the prepared composites. The advancement of a chemical reaction between TiCN and ZrB2 was suggested over the sintering process ...
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#1Kyung Il Kim (KITECH)H-Index: 3
#2Yeonju Oh (SNU: Seoul National University)H-Index: 4
Last. Heung Nam Han (SNU: Seoul National University)H-Index: 41
view all 8 authors...
An in-situ analysis of local strain accommodation on transformation induced plasticity (TRIP) aided multi-phase steel was performed with a correlative application of characterization techniques such as digital image correlation (DIC), electron backscatter diffraction (EBSD), and micro-mechanical testing. The local strain on the complex microstructure of the multi-phase steel was measured during a tensile test using an innovative DIC method (which does not employ artificial patterns), in conjunct...
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#1Hyoung Chan KimH-Index: 29
#2Eunnam BangH-Index: 6
Last. Suk-Ho HongH-Index: 19
view all 7 authors...
Abstract In this study, we investigated the material properties of tungsten mono-blocks undergone high heat flux test. The ITER-like tungsten mono-block specimens were fabricated by two kinds of joining methods. The tungsten-Cu interlayer joint was made by gas pressure casting and Cu interlayer-CuCrZr cooling tube were joined by hot radial pressing (HRP) or brazing method. To evaluate the integrity of the fabricated mono-blocks, high heat flux tests were done on the small mockups under cyclic he...
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#1Nojun Kwak (SNU: Seoul National University)H-Index: 27
#2Guensik Min (SNU: Seoul National University)H-Index: 1
Last. Heung Nam Han (SNU: Seoul National University)H-Index: 41
view all 7 authors...
Abstract Carbide reduces the ductility of tungsten and leads to brittle intergranular fractures. These fractures are inevitably formed in tungsten by carbon diffusion owing to graphite mold during spark plasma sintering. Here, we introduce protective foils made up of two different carbide-forming elements, molybdenum and tantalum, to minimize the carbide formation. Cross-sectional elemental mapping shows that the tantalum foil suppresses carbon diffusion into tungsten, while the molybdenum foil ...
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#1Won-hyuk Lee (KITECH)H-Index: 2
#2Yeonju Oh (SNU: Seoul National University)H-Index: 4
Last. Yanghoo Kim (KITECH)H-Index: 6
view all 5 authors...
Abstract The effects of Nb content on microstructures and resultant mechanical properties in Co-free CrFeNi2Nbx (x = 0, 0.2, 0.4, 0.55, 0.6, and 0.8) eutectic multicomponent alloys were investigated at room temperature. With increasing Nb content, the initial microstructure of a single face-centered cubic phase varied from hypoeutectic (0.2 0.6) with the formation of Fe2Nb-type Laves phase, and the compressive strength and hardness increased at the expense of ductility reduction. Although the ov...
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#1Yeonju Oh (SNU: Seoul National University)H-Index: 4
#2Han Chang-HeeH-Index: 3
Last. Heung Nam Han (SNU: Seoul National University)H-Index: 41
view all 5 authors...
Abstract Oxide dispersion-strengthened (ODS) alloys possess several advantages such as excellent high-temperature creep strength and oxidation/irradiation resistance. Lanthanide oxides as well as yttria (Y2O3) have been proven to act as efficient additives in Fe-based ODS alloys; however, their potential for addition to Ni-based alloys has been limited. In this study, we fabricated four types of Ni-based ODS alloys with the combined addition of Ti and either Y2O3, cerium dioxide (CeO2), lanthanu...
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#1Hyoung Chan KimH-Index: 29
#2Eunnam BangH-Index: 6
Last. Suk-Ho HongH-Index: 19
view all 8 authors...
Abstract In this study, we investigated thermal and microstructural properties of pure and dispersion strengthened tungsten fabricated by Spark Plasma Sintering (SPS) method in comparison to the tungsten materials produced by different commercial suppliers. We measured the thermal conductivity of the examined materials and compared them with chemical composition, density and microstructure of the samples. Thermal conductivity up to 900 ℃ was derived from thermal diffusivity and specific heat mea...
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#1Yeonju Oh (SNU: Seoul National University)H-Index: 4
#2Nojun Kwak (SNU: Seoul National University)H-Index: 27
Last. Heung Nam Han (SNU: Seoul National University)H-Index: 41
view all 5 authors...
Abstract An unusual room temperature mechanical behavior of pure tungsten is investigated by focusing on three specimens prepared with different microstructures: as-received (hot-rolled), recrystallized, and cold-rolled specimens. Contrary to ordinary expectations in metallic materials, only the cold-rolled specimen exhibits significant plastic deformation during tensile testing, with improved strength and ductility, while the recrystallized and the as-received specimens fail in the elastic regi...
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#1Yong Jin Kim (KU: Korea University)H-Index: 6
#2Sung-gyu Kang (SNU: Seoul National University)H-Index: 6
Last. Young Keun Kim (KU: Korea University)H-Index: 41
view all 7 authors...
Abstract Tungsten (W) thin films and nanostructures, particularly those having a beta (β)-phase, have attracted a large amount of attention lately because an ultrathin β-phase W film attached to a ferromagnetic layer can reverse the direction of magnetization upon current injection. However, in-depth microstructural studies including the phase transformation in W films as a function of thickness and post-deposition heat treatment temperature are rare. Here, we report the microstructural evolutio...
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