Si-Young Chang

• Korea Aerospace University

Ti-TiC composite materials were produced by spark plasma sintering (SPS) and electric discharge sintering (EDS) of spherical Ti powders with surface-embedded TiC. Hardness (HIT) and reduced elastic modulus (Er) were estimated using the nanoindentation method with an applied load of 100 mN, and compared with the micro-Vickers hardness value. The mic...

This investigates the microstructure and mechanical properties of Al hybrid material prepared by electromagnetic duo-casting to determine the effect of heat treatment. The hybrid material is composed of an Al-Mg-Si alloy, pure Al and the interface between the Al-Mg-Si alloy and pure Al. It is heat-treated at 373, 573 and 773K for 1h and T6 treated...

Elemental Ti and Al powders with a composition of Ti-25 at% Al, with and without 2 wt% steric acid as a process control agent, were ball-milled at 1000 rpm for 1 h using a Spex mill/mixer. The prepared powder mixture was then consolidated using an electric discharge sintering (EDS) with a 450 μF capacitor at an input voltage of 1.5–1.7 kV. The ball...

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 characterist...

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 mo...

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...

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...

Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100-150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in les...

The initial ferrite powders were subjected to high energy ball milling at 300rpm for 3h, and subsequently heat-treated at 573-1273K for 1h. Based on the observation of microstructure and measurement of magnetic properties, the heat-treatment effect was investigated. The size of initial powders was approximately 70μm. After milling, the powders with...

A single pulse of 20-35 kJ of input energy from a 450 mF capacitor was applied to a Ti rod. The electrical discharge process can produce rapid temperature increases of Ti from 569 to 2398°C in times as short as 159 μs, depending on the input energy. With an input energy greater than 25 kJ, a β→α allotropic transformation occurred, showing a typical...

Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat genera...

Porous-surfaced Ti implant compacts, with a solid core surrounded by a porous layer, were self-assembled by electro-discharge-sintering directly from spherical Ti powders. During an electro-discharge, instant high temperatures through the Ti powder column ranged from 1093 to 4925 °C were generated in times as short as 86-153 µsec. At the same time,...

A single pulse of 2.0 to 3.5 kJ of input energy from a 450 μF capacitor was applied in a low vacuum atmosphere to a commercially pure Ti rod. The electro-discharge process produced rapid temperature increases from 569 to 2516 °C in times as short as 159 μsec, depending on the input energy. The microstructure with equiaxed α grains was preserved aft...

A single pulse of 1.5 kJ/0.7 g of atomized spherical Ti powder from 300 μF capacitor was applied to produce the porous-surfaced Ti implant compact by electro-discharge-sintering (EDS). A solid core surrounded by porous layer was self-consolidated by a discharge in the middle of the compact in 122 μsec. Average pore size, porosity, and compressive y...

The ferrite powders were prepared by high energy ball-milling, and subsequently compacted under a pressure of 490MPa for 3min and sintered at 1273~1673K for 3h. The spherical shaped initial powders with a mean size of approximately 70μm were changed to irregular shaped powders of 230nm in a mean size after milling at 300rpm for 3h. The milled powde...

2·0 to 3·5 kJ of input energy as a single pulse from a 150 μF capacitor was applied to a 50% cold rolled Ti to induce rapid recrystallisation and surface modification. Using an input energy of 2·0 kJ, complete recrystallisation occurred over a period of 96 ms and the resulting microstructure was identical to that of a Ti before cold rolling. With a...

Porous Cu-Sn with controlled pore characteristics was synthesized by a freeze-drying and sintering process. CuO and SnO2 powders were selected as the source material, which are hydrogen-reduced to metallic Cu-Sn in the sintering stage. Camphene-based CuO-SnO2 slurries were prepared by milling at 60 A degrees C with a small amount of dispersant. Fre...

Some scattered neutron fields for the calibration of personal dosemeters and survey meters used for radiation protection purpose were constructed in the Radiation Calibration Laboratory (RCL) of Korea Atomic Energy Research Institute (KAERI). The radionuclide sources of 252Cf and 241AmBe were used for producing the neutron calibration fields with n...

Counting systems for direct measurement of the quantity of radioactive material deposited in the human body are used widely by radiation protection dosimetry services. Calibrations of in vivo counting systems are performed using anthropomorphic mannequins or dummies called phantoms. It is not, however, practicable to prepare phantoms corresponding...

A personal dosimetry system is required to measure the personal dose equivalent in a wide range of radiation fields as accurately as possible. For the construction of complete response functions of a dosemeter, varieties of monochromatic photon field covering energy ranges encountered in radiation protection practices are needed. So, 8 different qu...

A lineal energy, y and a specific energy, z are fundamental microdosimetric quantities for describing a radiation energy deposition event in a microscopic volume simulating a human tissue cell. They can be measured by using a low pressure Tissue Equivalent Proportional Counter (TEPC) with a so-called Bragg-Gray cavity principle. One of the advantag...

An extended Bonner Sphere (BS) set consisting of four polyethylene (PE) spheres and three PE spheres with an inserted lead shell to increase the detection efficiency for high energy neutron was used to measure the neutron spectra from the thick Pb target bombarded by 65 MeV electron at the Pohang Accelerator Laboratory (PAL). The response function...

The 304 stainless steel powders were prepared by high energy ball milling and subsequently sintered by spark plasma sintering, and the microstructural characteristics and micro-hardness were investigated. The initial size of the irregular shaped 304 stainless steel powders was approximately 42 . After high energy ball milling at 800 rpm for 5h, the...

Al-Mg-Si/Al hybrid alloy was prepared by Duo-casting and the mechanical behavior was evaluated based on their microstructure and mechanical properties. The hybrid aluminum alloy included the Al-Mg-Si alloy with fine eutectic structure, pure Al with the columnar and equiaxed crystals, and the macro-interface existing between Al-Mg-Si alloy and pure...

Porous Cu with macroscopically aligned channels was synthesized using a freeze-drying process. Camphene-based CuO slurry was prepared by milling at 60 °C with a small amount of dispersant. Freezing of a slurry was done at −25 °C while unidirectionally controlling the growth direction of the camphene. Pores were generated subsequently by sublimation...

The Fe-based self-fluxing alloy powders and TiC particles were ball-milled and subsequently compacted and sintered at various temperatures, resulting in the TiC particle-reinforced Fe self-fluxing alloy hybrid composite, and the microstructure and micro-hardness were investigated. The initial Fe-based self-fluxing alloy powders and TiC particles sh...

The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interfac...

The magnetic nano-structured Ba-Al ferrite powders were prepared by high energy ball milling under the conditions of various rotation rates and milling times. The micro structure was characterized by SEM, XRD and TEM, and the magnetic properties were obtained by VSM. As the rotation rate and milling time increased, the size of nano-sized particles...

The Fe-based self-fluxing alloy powders and SiC particles were mixed and milled by high energy ball-milling, and their microstructure and micro-hardness were investigated after subsequent compaction and sintering. The initial alloy powders with a mean size of approximately 80 microm were fined to 2.1 microm after milling at 800 rpm for 5 h. However...

In order to fabricate the porous metal with controlled pore characteristics, unique processing by using metal oxide powder as the source and camphene as the sublimable material is introduced. CuO powder was selected as the source for the formation of Cu metal via hydrogen reduction. Camphene-based CuO slurry, prepared by milling at 47^{\circ}C with...

The shape of a dendrite tip has long been approximated by a paraboloid of revolution, but many attempts have been made as well to more accurately match the dendrite tip profile using other mathematical functions: power function, 4th order polynomial, and hyperbolic function. In the present work, dendrite tip shapes were matched by parabolic functio...

The CuO and SnO2 powders with the mean powder size of approximately 2 mm were mixed and ball-milled at a rotation rate of 800 rpm for 5 h, their microstructure and reduction characteristics were investigated. The mixed powder size became smaller to approximately 0.7 mm after milling, which consisted of the nano-sized particles with approximately 45...

The effect of hydrogen reduction temperature on the properties of Fe–Ni powders was described. The mixed powders of Fe-oxide and NiO were prepared by chemical solution mixing of nitrates powders and calcination at 350 °C for 2 h in air. The calcined powders formed small agglomeration with an average particle size of 100 nm. The microstructure and m...

Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging fr...

In present work, amorphous TiCuNi powders were fabricated by mechanical alloying process. Amorphization and crystallization behaviors of the TiCuNi powders during high-energy ball milling and subsequent microstructure changes were studied by X-ray diffraction and transmission electron microscope. TEM samples were prepared by the focused ion beam te...

Mg-1.0wt%Zn-2.0wt%Y alloy powders were produced by gas atomization, and subsequently sintered by spark plasma sintering (SPS). The SPSed Mg-1.0wt%Zn-2.0wt%Y alloy, which showed a microstructure of well-bonded grains containing nano-sized powders of approximately 100 nm in diameter, was coated by a plasma electrolytic oxidation (PEO) method. Microst...

Sm-16.7wt%Co alloy powders were prepared by a high energy ball milling under various milling times, and their micro-structure and magnetic properties were investigated. After 5 h milling, the irregular shaped powders were changed to spherical shape and the size decreased to approximately 5 µm. Based on TEM results, the obtained powders consisted of...

Mg-6 wt.%Al-1 wt.%Zn alloy powders were produced by gas atomization, and subsequently compacted and sintered under various conditions of temperature, time, and pressure. The bulk Mg-6 wt.%Al-1 wt.%Zn alloy was coated by the plasma electrolytic oxidation (PEO) method. The optimum condition of compaction and sintering for PEO coatings was established...

The aging characteristics of gas atomized Mg-6 wt.% Al-1 wt.% Zn alloy were investigated and compared to those of cast Mg-6 wt.% Al alloy. The gas atomized Mg-6 wt.% Al-1wt.% Zn alloy powders had spherical morphology between 1 and 100 \mu m in diameter. After compaction under the pressure of 700 MPa at 320^{\circ}C for 10 min, the Mg-6 wt.% Al-1 wt...

Tensile properties of AZ91D magnesium alloy coated by Plasma Electrolytic Oxidation method for various coating times were investigated. The coatings on AZ91D magnesium alloy showed porous microstructure, and became thicker with increasing the coating time. After tensile test, the coated AZ91D magnesium alloy had lower tensile strength and elongatio...

Pure Mg and Mg-6wt.%Al alloy were coated by the plasma electrolytic oxidation with various coating times and the microstructural and mechanical characteristics of the coatings were investigated. The coatings on pure Mg and Mg-6wt.%Al alloy consisted of MgO and Mg2SiO4. The surface roughness and thickness of the coatings became larger as the coating...

The Mg-6wt%Al-1wt%Zn alloy powders mixture produced by gas atomization were spark plasma sintered (SPSed). The SPSed sample was coated by plasma electrolytic oxidation (PEO) method, and the microstructure, mechanical and corrosion properties were investigated and compared to the normally sintered sample. The SPSed sample exhibited a microstructure...

The characteristics, such as roughness, thickness, microhardness and corrosion resistance, of plasma electrolytic oxide coatings on AZ91D alloy were investigated under the processing condition of various coating times. The coatings on AZ91D alloy consisted of MgO, and oxides. The surface roughness and thickness of coatings became larger with increa...

Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation (PEO) method. The Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear resistance. After PEO coating, however, the microhardness and wear resistance of coatings on Mg-6 wt pct Al alloy showed a tenden...

Plasma electrolytic oxidation (PEO) treatment was performed on cast Mg-6 wt%Al alloy solution-treated at 693K for 16h and aged at 498K. The surface roughness, thickness, micro-hardness, wear and corrosion properties of coatings on solution-treated and aged Mg-6 wt%/Al alloy were investigated. The coatings on aged Mg-6 wt%Al alloy had thinner layer...

The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was co...

The bi-materials with Al-Mg alloy and its composites reinforced with SiC and particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under , and then the mixtures compacted under 400 MPa were sintered at for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relat...

Ceramic coatings were synthesized on pure Mg and binary Mg-7.1wt%Al alloy by plasma electrolytic oxidation (PEO) technique, and the effect of current ratio, C2/C1, ranging from 0.2 to 0.85 on their mechanical and electrochemical properties was investigated. As the C2/C1 ratio increased, the thickness of the coating layer increased, while surface ro...

Pure Mg, binary Mg-5.6wr%Al, Mg-1.0wt%Si and Mg-7.5wt%Zn alloys were coated by plasma electrolytic oxidation (PEO) method, and their wear properties were investigated and discussed based on surface roughness, thickness and component of coatings. All coatings showed porous layer with some volcano top-like pores on the surface and the non-uniform thi...

The hybrid materials with Al-Mg alloy and its composites reinforced with SiC and Al2O3 particles were prepared by conventional powder metallurgy method. The Al-5wt%Mg and composite mixtures were compacted under a pressure of 400MPa and sintered at 873K for 5h. The obtained hybrid materials with Al-Mg/SiCp composite showed the higher relative densit...

The sintering characteristics and mechanical properties of 7xxx series Al composite were investigated. AMB7775 (Al–7.0Zn–2.5Mg–1.0Cu) was used as a starting material, and SiC were added as dispersed particles to AMB7775 in order to confirm the effect of the ceramic particles on the Al matrix in composite materials. In the case of the SiC-reinforced...

Ceramic coatings were synthesized on pure magnesium, binary Mg-Al and Mg-Zn alloys by plasma electrolytic oxidation (PEO) technique, and their mechanical and electrochemical properties were investigated. The coatings showed porous microstructure and some volcano top-like pores on the surface. The coatings on Mg-Al alloys consisted of MgO, MgAl2O4 a...

The effect of working temperature on microstructure and mechanical properties of ultrafine grained monolithic Al and Al-5vol.%SiCp composite processed by accumulative roll bonding (ARB) was studied. The ARB was performed up to eight cycles (an equivalent strain of ~6.4) without lubricant. The working temperature was varied from ambient temperature...

The bimodal-structured materials composed of Al-5wt%Mg alloy and its composites reinforced with SiC and Al2O3 particles were prepared by ball-milling and subsequent compaction under the pressure of 350MPa and sintering at temperatures ranging from 973K to 1173K for 1h, 3h and 5h. The macro-interface between Al-Mg and Al-Mg/ Al2O3 composite was macr...

The aging behavior of sintered Al composites with various ceramic contents was investigated. 2xxx series blended powder was used as the starting powder. Ceramic contents were 0 wt.% and 5 wt.%. The blended powders were compacted at 250 MPa. The sintering process was performed at 620oC for 60 min in a N2 atmosphere. After sintering, each part was so...

Fe/MgO nanocomposites, which are applicable to high frequency electronic devices, were fabricated by ultrasonic spray pyrolysis and selective reduction processes. Transmission electron micrographs showed that nano ferromagnetic Fe particles were isolated by MgO insulating matrix. With the increase of the reduction temperature, the particle size and...

Aging characteristics and mechanical properties of commercial 7xxx series Al composites were investigated from viewpoint of ceramic contents. After sintering process, sintered densities of blended and composite powder were 95 and 97%, respectively. Each part was solution-treated at 475^{\circ}C for 60 min and aged 175^{\circ}C. And two-step aging w...

Deformation characteristics of a newly developed wave-typed heat sink during mechanical assembly of fin-base were analyzed by using the Ansys program. The original points a and b marked in the fin and base moved to the opposite y direction with increasing pressure, while their movements to x direction were relatively small. It was evident that at l...

Plasma electrolytic oxide coatings were produced on both pure magnesium and binary Mg-Al alloys containing 3, 6, 7 wt% Al, and the effect of Al on the characteristics of coatings was investigated under the processing conditions of various coating times and current. The coatings on Mg-Al alloys showed porous microstructure and some volcano top-like...

Copper via filling is an important factor in 3D stacking interconnection of SiP (system in package). As the packaging density is getting higher, the size of via is getting smaller. When DC electroplating is applied, a defect-free hole cannot be obtained in a small size hole. To prevent the defects in holes, pulse and pulse reverse current was appli...

The hydrogen-reduction behavior of W-oxides in ball-milled powder mixtures of W- and Cu-oxides was investigated by microstructural analysis and humidity change measurement in the reduction process. The refinement and homogeneous mixing of powders by the ball-milling process induced a decrease in hydrogen-reduction temperature of W-oxides and the re...

Both the Al-5wt%Mg powder mixture and Al-5wt%Mg/SiCp composite mixture were separately ball-milled for 50h, followed by compaction under a pressure of 350MPa. To obtain the bi-materials, the compacted Al-5wt%Mg and Al-5wt%Mg/SiCp composites were bonded by sintering at 873K-1173K for 1-3h. At a relatively low temperature, 873K, the sound bi-material...

7xxx series Al alloy has the most attractive properties including its excellent high specific strength, stress corrosion cracking and corrosion-resistance. However, in case of the Al-Zn system, the liquid phase has a transient aspect because of the high solid solubility of Zn in Al. Therefore, transient liquid phase sintering behavior was observed...

The microstructure and tensile deformation characteristics in the commercial 5083 Al alloy after equal channel angular pressing (ECAP) at 373 and 473 K were investigated and compared with those of one reannealed at 473 K for 1 h after ECAP at 373 K. All specimens revealed nano-structure with grains of ∼300 nm and no distinct grain boundaries except...

Heat flow characteristics in the newly developed Wave Heat Sink were analyzed under natural and forced convections by Icepak program using the finite volume method. Temperature distribution and thermal resistance of Wave Heat Sink with/without air vent hole on the top of fin were compared with those of a commercial Al extruded heat sink(Intel Heat...

The bi-materials composed of and its composite reinforced with SiC particles were prepared by ball-milling and subsequent sintering process. The size of powder in Al-Mg/SiCp mixture decreased with increasing ball-milling time, it was saturated above 30 h when the ball and powder was in the ratio of 30 to 1. Both powders mixture and mixture were com...

Heat analysis of the plate type and wave type heat sink were carried out by using computational simulation. The heat resistance and air flow of two heat sink models were analysed according to natural and forced convection condition and positions of fan. When a fan was at the position of z-axis and y-axis in forced convection, the heat resistances o...

The nano-structure in the commercial 5083 Al alloy was introduced by the equal channel angular pressing technique. The nano-sized grains of ~300 nm were obtained after 8 ECAPs at 373 K and 473 K. It was also obvious that much improvement in strength was obtained at lower pressing temperature, 373 K, than 473 K. In particular, there were mainly two...

TiO2, Al2O3 and SiO2 single layer films were deposited in the oxygen gas atmosphere by plasma assisted e-beam evaporation(PAEBE) at various RF power and low temperature on p-type Si wafer(100) and glasses. The effects of plasma assistance on the optical and microstructual properties of three kinds of single layer films were investigated. In additio...

The commercial AZ31 and AZ61 Mg alloys were subjected to equal channel angular pressing (ECAP) after hot rolling at 673 K. The hot-rolled AZ31 alloy could be ECA pressed at 493 K. The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10μm. Despite the dynamic recrystallizati...

Aluminum based metal matrix composite (MMC) was processed by accumulative roll bonding (ARB) for ultra grain refinement and high strengthening. The ARB process up to 4 cycles was performed for the composite with 5vol.%SiC at ambient temperature under unlubricated conditions. The ARB of unreinforced aluminum powder compact was also performed for com...

The commercial pure Mg, AZ31 and AZ61 alloys were severly plastic-deformed through equal channel angular pressing (ECAP). The grain size of pure Mg was decreased from 400 to 80 mum after ECAP and the 4 ECA pressed AZ31 alloy revealed the mixed microstructure of fine grains of less than 5 mum and coarser grains of approximately 5 similar to 10 mum....

Personal neutron dosimetry is quite a difficult area because a neutron is always accompanied with gamma radiation, which is required of a capability for mixed field dosimetry. CaSO4:Dy phosphor is known to have a very high sensitivity to gamma radiation, but the neutron capture cross section of the constituents of CaSO4:Dy are so small that the int...

The nano-structure in the commercial 5083 Al alloy was introduced by the equal channel angular pressing technique. The nano-sized grains of similar to300 nm were obtained after 8 ECAPs at 373 K and 473 K. It was also obvious that much improvement in strength was obtained at lower pressing temperature, 373 K, than 473 K. In particular, there were ma...

Aluminum based metal matrix composite (MMC) was processed by accumulative roll bonding (ARB) for ultra grain refinement and high strengthening. The ARB process up to 4 cycles was performed for the composite with 5vol.%SiC at ambient temperature under unlubricated conditions. The ARB of unreinforced aluminum powder compact was also performed for com...

The commercial AZ31 and AZ61 Mg alloys were subjected to equal channel angular pressing (ECAP) after hot rolling at 673 K. The hot-rolled AZ31 alloy could be ECA pressed at 493 K. The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10 mum. Despite the dynamic recrystalliza...

TiO2, Al2O3 and SiO2 single layer films were deposited in the oxygen gas atmosphere by plasma assisted e-beam evaporation(PAEBE) at various RF power and low temperature on p-type Si wafer(100) and glasses. The effects of plasma assistance on the optical and microstructual properties of three kinds of single layer films were investigated. In additio...

The Mg chips were recycled using powder metallurgy method and was also reinforced with SiC particles of Vf 10%. The mechanical characteristics of recycled Mg and SiCp/Mg composite were investigated by microhardness and tensile tests, and were compared with those of cast Mg. The microhardness and tensile strength of recycled Mg produced with chips o...

An attempt has been made to measure the temperature dependence of dynamic Young’s modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was employed using a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young’s modulus and i...

The 6061 (Al–1.01 wt% Mg–1.07 wt% Si) Al alloy was fabricated by powder metallurgy, and then subjected to equal channel angular pressing. The microstructure and mechanical properties such as microhardness and tensile properties of the equal channel angular pressed P/M 6061 Al alloy were investigated. The P/M 6061 Al alloy had an initial grain size...

The difficult-to-work Mg alloys was subjected to equal channel angular pressing (ECAP) under a condition of various pressing temperatures. Pure Mg was susceptible to shear localization during ECAP; surface cracking occurred along to the direction of shear localization at lower temperatures than 573 K. Uniform flow occurred at 573 K, resulting in th...

The difficult-to-work Mg alloys was subjected to equal channel angular pressing (ECAP) under a condition of various pressing temperatures. Pure Mg was susceptible to shear localization during ECAP; surface cracking occurred along to the direction of shear localization at lower temperatures than 573 K. Uniform flow occurred at 573 K, resulting in th...

A submicrometer-grained structure was introduced in a commercial 5083 Al alloy by imposing an effective strain of ∼8 through equal channel angular pressing. In order to examine the low-temperature superplastic behavior, the as-equal channel angular pressed (as-ECAP) samples were tensile tested in the strain rate range of 10−5 to 10−2 s−1 at tempera...

Control of lamellar orientation in unidirectionally solidified Ti-48Al PST crystals has been attempted by an optical floating zone method using various seed crystals of Ti-(48-57)Al alloys. Regardless of the seed crystals, the Ti-48Al PST crystals can be grown without any difficulty. However, the lamellar orientation can never reproducibly be contr...

Spatial variation of field-emission currents in boron-doped polycrystalline diamond thin films grown by microwave plasma-assisted chemical-vapor deposition was investigated. Random distribution of electron emission sites was observed in microscale and the electron emission was inhomogeneous. Electron emission current was significantly increased for...

The 6061 Al-10 vol% SiCw composites were prepared by powder metallurgy with the powders having the different sizes, i.e. < 30 μm and 30 μm <. The composites were subjected to equal channel angular pressing (ECAP) under various conditions and the microstructural changes during ECAP were examined. A special focus was made on the effect of ECAP condit...

The 6061 Al alloy based composites reinforced with 10 vol% SiC whiskers were prepared by powder metallurgy with the powders having the different sizes, i.e. The composites were subjected to equal channel angular pressing (ECAP) at various conditions and the microstructural changes during ECAP were examined In the composites SiC whiskers were cluste...

Equal channel angular pressing (ECAP) was conducted on the two grades of low carbon steel, with or without vanadium, in order to produce an ultarfine grained structure. As a result, the ferrite grains were refined from 30 mum to 0.2similar to0.3 mum. The strength of the ECAPed steels increased remarkably, over twice of the strength of the steels be...

CaSO:Dy thermoluminescence dosimeter (TLD) is widely used as a personal or environmental dosimeter because of its high sensitivity to radiation. There are many methods to make pellets from the TL phosphorss[l-5]. Sintered pellets were made from a mixture of CaSO:Dy phosphor and Teflon powder is the most common method. But this method has disadvanta...

Several aspects of equal channel angular pressing (ECAP) of steels, aluminum alloys and pure titanium were examined. They include grain refinement, microstructural modification, superplasticity, mechanical properties, etc. The grain refinement process of steels and aluminum alloys during ECAP appeared to be due to slip band formation, but that of t...

The energy dependence of a CaSO4:Dy TL phosphor for 21 monoenergetic photons of energy ranging from 0.01 to 3MeV was calculated by using MCNP4A code. The calculation results show good agreement with those of other authors within ±5% relative error. Calculations and experiments are also performed to determine the energy dependence of CaSO4:Dy phosph...

The characteristics of high temperature deformation in Mg-Y alloys were investigated and compared with those of pure Mg. The effect of Y on slip and twinning deformations was also discussed in respect to the lattice parameter with temperature. Pure Mg displays a gradual decrease in proof stress with increasing temperature. However, the proof stress...

The microstructure and tensile properties of bi-materials consisting of the unreinforced magnesium, the macro-interface and composite reinforced with SiC whiskers were investigated. The macro-interface has diffuse interface characteristics, its thickness is about 7∼10 μm. It has been found that the tensile strength of the bi-materials at R.T. is lo...

The microstructural and mechanical characteristics of component with the macro-interface between unreinforced magnesium and composite manufactured by squeeze casting were determined. The effect of thermal cycling on the tensile properties of the component with the macro-interface, which is a potential site of cyclic stress formation, was investigat...

An ultra-fine grained (UFG) structure was introduced in a commercial 5083 Al alloy with an initial grain size of ∼ 200 \\micron using the equal channel angular pressing (ECAP) technique. ECAP was successfully conducted at 473 K on the same sample up to a total of 8 pressings through the die such that the sample was rotated 180° around its longitudi...

Sintered LiF:Mg,Cu,Na,Si thermoluminescence (TL) pellets were developed for application in radiation dosimetry. In the present study, the TL dosimetric properties of LiF:Mg,Cu,Na,Si TL pellets have been investigated for emission spectrum, dose response, energy response, and fading characteristics. LiF:Mg,Cu,Na,Si TL pellets were made by using a sin...