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Wyszukujesz frazę "Chang, K." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
Atomistic Analysis Of Radiation-Induced Segregation In Ion-Irradiated Stainless Steel 316
Analiza w skali atomowej indukowanej promieniowaniem segregacji w stali nierdzewnej 316
Autorzy:
Lee, G.-G.
Jin, H.-H.
Chang, K.
Lee, B. H.
Kwon, J.
Powiązania:
https://bibliotekanauki.pl/articles/354713.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
atom probe tomography (APT)
radiation-induced segregation (RIS)
ion irradiation
irradiation defects
stainless steel
APT
RIS
stal nierdzewna
segregacja
Opis:
Stainless steel (SS) is a well-known material for the internal parts of nuclear power plants. It is known that these alloys exhibit radiation-induced segregation (RIS) at point defect sinks at moderate temperature, while in service. The RIS behavior of SS can be a potential problem by increasing the susceptibility to irradiation-assisted stress corrosion cracking. In this work, the RIS behavior of solute atoms at sinks in SS 316 irradiated with Fe4+ ions were characterized by atom probe tomography (APT). There were torus-shaped defects along with a depletion of Cr and enrichment of Ni and Si. These clusters are believed to be dislocation loops resulting from irradiation. The segregation of solutes was also observed for various defect shapes. These observations are consistent with other APT results from the literature. The composition of the clusters was analyzed quantitatively almost at the atomic scale. Despite the limitations of the experiments, the APT analysis was well suited for discovering the structure of irradiation defects and performing a quantitative analysis of RIS in irradiated specimens.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1179-1184
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Vacuum Hot-Press Process on The Sintered Characteristics and Mechanical Properties of A High-Density Cr-31.2 Mass% Ti Alloy
Autorzy:
Chang, S.-H.
Li, C.-L.
Huang, K.-T.
Yang, T.-H.
Powiązania:
https://bibliotekanauki.pl/articles/356911.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cr-31.2 mass% Ti alloy
vacuum hot-press sintering
relative density
TRS
electrical conductivity
Opis:
In this study, two different compositions of submicron-structured titanium (760 nm) and micron-structured chromium (4.66 μm) powders were mixed to fabricate Cr-31.2 mass% Ti alloys by vacuum hot-press sintering. The research imposed various hot-press sintering pressures (20, 35 and 50 MPa), while the sintering temperature maintained at 1250°C for 1h. The experimental results showed that the optimum parameters of the hot-press sintered Cr-31.2 mass% Ti alloys were 1250°C at 50 MPa for 1h. Also, the relative density reached 99.94%, the closed porosity decreased to 0.04% and the hardness and transverse rupture strength (TRS) values increased to 81.90 HRA and 448.53 MPa, respectively. Moreover, the electrical conductivity is enhanced to 1.58 × 104 S·cm-1 However, the grain growth generated during the high-temperature and high-pressure of the hot-press sintering process resulted in the grain coarsening phenomenon of the Cr-31.2 mass% Ti alloys after 1250°C hot-press sintering at 50 MPa for 1h. In addition, the Cr-31.2 mass% Ti alloys were fabricated with the submicron-structured titanium (760 nm) and chromium (588 nm) powders showed more effective compaction than the micron-structured titanium (760 nm) and chromium (4.66 μm) powders did. The closed porosity decreases to 0.02% and the hardness values increase to 83.23 HRA. However, the agglomeration phenomenon of the Cr phase and brittleness of the TiCr2 Laves phases easily led to a slight decrease in TRS (400.54 MPa).
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 4; 1715-1723
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous Formation of Titanium Nitride on the Surface of a Ti Rod Induced by Electro-Discharge-Heat-Treatment in an N2 Atmosphere
Autorzy:
Lee, W. H.
Yoon, Y. H.
Kim, Y. H.
Lee, Y. K.
Kim, J. Y.
Chang, S. Y.
Powiązania:
https://bibliotekanauki.pl/articles/352477.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
titanium
surface modification
diffusion
heat treatment
XPS
Opis:
A single pulse of 2.0 to 3.5 kJ of input energy from a 450 mF capacitor was applied to a commercially pure Ti rod in a N2 atmosphere. The surface of the Ti rod transformed from TiO2 into titanium nitride in times as short as 159 msec, providing a bimodal morphology of the cross-section. A much higher value of hardness that was observed at the edge of the cross-section was attributed to nitrogen-induced solid-solution hardening that occurred during the electrical discharge process. The activation energy (Ea) for the diffusion process was estimated to be approximately 86.9 kJ/mol. Results show that the electrical discharge process is a possible potential method for the nitriding of Ti; advantages include a short processing time and control of the nitrided layer without dimensional changes.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1281-1285
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-Consolidation and Surface Modification of Mechanical Alloyed Ti-25.0 at.% Al Powder Mixture by Using an Electro-Discharge Technique
Autorzy:
Chang, S. Y.
Jang, H. S.
Yoon, Y. H.
Kim, Y. H.
Kim, J. Y.
Lee, Y. K.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/354212.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sintering
mechanical alloying
powder consolidation
intermetallic compounds
titanium aluminides
Opis:
Electrical discharges using a capacitance of 450 μF at 0.5, 1.0, and 1.5 kJ input energies were applied in a N2 atmosphere to obtain the mechanical alloyed Ti3Al powder without applying any external pressure. A solid bulk of nanostructured Ti3Al was obtained as short as 160 μsec by the Electrical discharge. At the same time, the surface has been modified into the form of Ti and Al nitrides due to the diffusion process of nitrogen to the surface. The input energy was found to be the most important parameter to affect the formation of a solid core and surface chemistry of the compact.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1293-1297
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-Consolidation Mechanism of Ti5Si3 Compact Obtained by Electro-Discharge-Sintering Directly from Physically Blended Ti-37.5 At.% Si Powder Mixture
Autorzy:
Chang, S. Y.
Cheon, Y. W.
Yoon, Y. H.
Kim, Y. H.
Kim, J. Y.
Lee, Y. K.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/353022.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sintering
mechanical alloying
powder consolidation
intermetallic compounds
titanium silicide
Opis:
Characteristics of electro-discharge-sintering of the Ti-37.5at.% Si powder mixture was investigated as a function of the input energy, capacitance, and discharge time without applying any external pressure. A solid bulk of Ti5Si3 was obtained only after in less than 129 μsec by the EDS process. During a discharge, the heat is generated to liquefy and alloy the particles, and which enhances the pinch pressure can condensate them without allowing a formation of pores. Three step processes for the self-consolidation mechanism during EDS are proposed; (a) a physical breakdown of oxide film on elemental as-received powder particles, (b) alloying and densifying the consolidation of powder particles by the pinch pressure, and (c) diffusion of impurities into the consolidated surface.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1299-1302
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Si/ZnO nanorods with Ag nanoparticles/AZO heterostructures in PV applications
Autorzy:
Gwóźdź, K.
Płaczek-Popko, E.
Gumienny, Z.
Zielony, E.
Pietruszka, R.
Witkowski, B. S.
Wachnicki, Ł.
Gierałtowska, S.
Godlewski, M.
Chang, L. B.
Powiązania:
https://bibliotekanauki.pl/articles/201432.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solar cells
ZnO
Si
heterojunction
nanorods
nanoparticles
ogniwa słoneczne
nanopręty
nanocząstki
Opis:
Our studies focus on test structures for photovoltaic applications based on zinc oxide nanorods grown using a low-temperature hydrothermal method on a p-type silicon substrate. The nanorods were covered with silver nanoparticles of two diameters – 20–30 nm and 50–60 nm – using a sputtering method. Scanning electron microscopy (SEM) micrographs showed that the deposited nanoparticles had the same diameters. The densities of the nanorods were obtained by means of atomic force microscope (AFM) images. SEM images and Raman spectroscopy confirmed the hexagonal wurtzite structure of the nanorods. Photoluminescence measurements proved the good quality of the samples. Afterwards an atomic layer deposition (ALD) method was used to grow ZnO:Al (AZO) layer on top of the nanorods as a transparent electrode and ohmic Au contacts were deposited onto the silicon substrate. For the solar cells prepared in that manner the current-voltage (I-V) characteristics before and after the illumination were measured and their basic performance parameters were determined. It was found that the spectral characteristics of a quantum efficiency exhibit an increase for short wavelengths and this behavior has been linked with the plasmonic effect.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 3; 529-533
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Modification of Self-Consolidated Microporous Ti Implant Compacts Fabricated by Electro-Discharge-Sintering in Air
Autorzy:
Jo, Y. J.
Yoon, Y. H.
Kim, Y. H.
Chang, S. Y.
Kim, J. Y.
Lee, Y. K.
Van Tyne, C. J.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/356790.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
titanium
implant
porous
sintering
X-ray photoelectron spectroscopy (XPS)
Opis:
A single pulse of 0.75-2.0 kJ/0.7g of atomized spherical Ti powders from 300 mF capacitor was applied to produce a microporous Ti implant compact by electro-discharge-sintering (EDS). A solid core in the middle of the compact surrounded by a microporous layer was found. X-ray photoelectron spectroscopy was employed to study the surface characteristics of the EDS Ti compact and it revealed that Ti, C and O were the main constituents on the surface with a smaller amount of N. The surface was lightly oxidized and was primarily in the form of TiO2 resulting from the air oxidation during EDS processing. The lightly oxidized surface of the EDS compact also exhibited Ti nitrides such as TiN and TiON, which revealed that the reaction between air constituents and the Ti powders even in times as short as 128 msec.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1287-1291
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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