Zr-Ti alloy powders were successfully synthesized by magnesium thermal reduction of metal chlorides. The evaporated and mixed gasses of were injected to liquid magnesium and the chloride components were reduced by magnesium leading to the formation of . The released Zr and Ti atoms were then condensed to particle forms inside the mixture of liquid magnesium and magnesium chloride, which could be dissolved fully in post process by 1~5% HCl solution at room temperature. By the fraction-control of individually injected and gasses, the final compositions of produced alloy powders were changed in the ranges of Zr-0 wt.%~20 wt.%Ti and their purity and particle size were about 99.4% and the level of several micrometers, respectively.

현재 지구온난화 등의 환경문제로 인해 각종 산업분야에서 정량화에 대한 요구가 증대되어 해양산업에도 그 수요가 증가하고 있는 실정이다. 따라서 본 연구에서는 차세대 경량화 재료인 마그네슘이 활용되기 위해서 반드시 극복해야할 가장 중요한 특성인 내식특성에 대하여 고찰하고, 그 내식특성 향상을 위한 마그네슘 박막의 Morphology나 결정배향성의 영향을 해명하고자 하였다. 실험결과로부터 제작한 Mg 박막의 전기화학적 내식특성은 Ar 가스압이 높은 조건에서 제작한 막일수록 내식특성이 우수하였다. 이러한 경향은 표면 및 단면의 Morphology와 결정배향성과의 상관관계를 통하여 설명 가능하였다.

In this research, the refinement behavior of the coarse magnesium powders fabricated by gas atomization was investigated as a function of milling time using a short duration high-energy ball milling equipment, which produces fine powders by means of an ultra high-energy within a short duration. The microstructure, hardness, and formability of the powders were investigated as a function of milling time using X-ray diffraction, scanning electron microscopy, Vickers micro-hardness tester and magnetic pulsed compaction. The particle morphology of Mg powders changed from spherical particles of feed metals to irregular oval particles, then platetype particles, with increasing milling time. Due to having HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, resulting in producing plate-type powders. With increasing milling time, the particle size increased until 5 minutes, then decreased gradually reaching a uniform size of about 50 micrometer after 20 minutes. The relative density of the initial power was 98% before milling, and mechanically milled powder was 92~94% with increase milling time (1~5 min) then it increased to 99% after milling for 20 minutes because of the change in particle shapes.

The ultrafine titanium carbonitride () particles below 100 nm in mean size, including various carbon and nitrogen contents (x=0.55~0.9, y=0.1~0.5), were successfully synthesized by new Mg-thermal reduction process. Nanostructured sub-stoichiometric titanium carbide () particles were initially produced by the magnesium reduction of gaseous at and post heat treatments in vacuum were performed for 2 hrs to remove residual magnesium and magnesium chloride mixed with . Finally, well C/N-controled phases were successfully produced by nitrification heat treatment under normal gas atmosphere at for 2 hrs. The values of purity, mean particle size and oxygen content of produced particles were about 99.3%, 100 nm and 0.2 wt.%, respectively.

Different types magnesium hydroxide groups have been obtained using the hydrothermal precipitation technique from magnesium sulfate and calcium carbonate solution. The Mg atom coordinated around O atom of SO42- in another layer to form a multi-layer structure crystal. The influence of synthesis parameters on the morphological characteristics and size of magnesium hydroxide groups precipitated in aqueous were investigated such as different of additive and pH. Magnesium hydroxide groups were decomposed gradually and converted finally to MgO particles after heated in air temperature up to 1050℃. The particle size and it's distribution morphology, crystal phase and thermal behavior of the samples were characterized through XRD, SEM, EDS, and TG/DTA.

Numerical simulations of the powder extrusion need an appropriate pressure-dependent constitutive model for densification modeling of the magnesium powders. The present research investigated the effect of representative powder yield function of the critical relative density model. We could obtain reasonable physical properties of pure magnesium powders using cold isostatic pressing. The proposed densification model was implemented into the finite element code. The finite element analysis was applied to simulation of powder extrusion of pure magnesium powder in order to investigate the densification and processing load at room temperature.

마그네슘 시비농도를 인위적으로 조절하여 '매향' 딸기를 관비재배하면서 Mg의 시비수준이 생장과 결핍증상 발현에 미치는 영향을 구명하고, 건전생육을 유지할 수 있는 식물체 및 토양의 한계농도를 밝히기 위하여 본 연구를 수행하였다. 마그네슘 결핍증상은 하위엽에서 발생하였으며, 초기에 하위엽의 엽맥 사이에서 반점 형태의 황화현상이 나타난 후 점차 반점 부위가 확산되어 엽맥간 황화현상으로 발전하였다 또한 증상이 심해지면서 엽맥 사이가 검게 변하고, 하위엽 선단의 갈변 및 괴사하는 증상이 발생하였다. Mg시비농도를 조절하여 관비하고 정식 120일 후에 지상부 생육을 조사한 결과 Mg 1.0 또는 2mM의 처리에서 생육이 우수하였으며, 0.5 이하나 4mM 이상으로 Mg 시비농도를 조절한 처리의 생장이 저조해지는 경향이었다. 건물중은 마그네슘 시비농도에 대하여 3차 곡선회귀적인 반응을 보였으며 식물체당 약 8.2g의 건물중을 생산할 때 정점이 형성되었다. 최대 생장량의 90%를 최저 한계점으로 간주하면 식물체당 7.4g 이상의 건물중을 생산하기 위해서는 Mg 함량이 0.30~0.65%의 범위에 포함되도록 시비해야 하며, 최적 시비농도는 약 2mM 이라고 판단하였다. 또한, 최대 생산량인 식물체당 생체중 36.2g의 90%를 최저 및 치고 한계점으로 간주 할 경우 엽병 추출액의 Mg농도가 19~40mg·kg-1의 범위에 포함되도록 시비해야 한다고 판단하였다.

Carbon was known to be one of effective additives which can improve the flux pinning of at high magnetic fields. In this study, glycerin was selected as a chemical carbon source for the improvement of critical current density of . In order to replace some of boron atoms by carbon atoms, the boron powder was heat-treated with liquid glycerin. The glycerin-treated boron powder was mixed with an appropriate amount of magnesium powder to composition and the powder pallets were heat treated at for 30 min in a flowing argon gas. It was found that the superconducting transition temperature of prepared using glycerin-treated boron powder was 36.6 K, which is slightly smaller than (37.1 K) of undoped . The critical current density of was higher than that of undoped and the improvement effect was more remarkable at higher magnetic fields. The , decrease and increase associated with the glycerin treatment for boron powder was explained in terms of the carbon substitution to boron site.

The total energy and strength of Mg alloy doped with Al, Ca and Zn, were calculated using thedensity functional theory. The calculations was performed by two programs; the discrete variational Xα (DV-Xα) method, which is a sort of molecular orbital full potential method; Vienna Ab-initio Simulation Package(VASP), which is a sort of pseudo potential method. The fundamental mixed orbital structure in each energylevel near the Fermi level was investigated with simple model using DV-Xα. The optimized crystal structurescalculated by VASP were compared to the measured structure. The density of state and the energy levels ofdopant elements was discussed in association with properties. When the lattice parameter obtained from thisstudy was compared, it was slightly different from the theoretical value but it was similar to Mk, and weobtained the reliability of data. A parameter Mk obtained by the DV-Xα method was proportional toelectronegativity and inversely proportional to ionic radii. We can predict the mechanical properties becauseis proportional to hardness.

Magnesium and magnesium alloys are promising materials for light weight and high strength applications. In order to obtain homogeneous and high quality products in powder compaction and powder forging processes, it is very important to control density and density distributions in powder compacts. In this study, a model for densification of metallic powder is proposed for pure magnesium. The mode] considers the effect of powder characteristics using a pressure-dependent critical density yield criterion. Also with the new model, it was possible to obtain reasonable physical properties of pure magnesium powder using cold iso-state pressing. The proposed densification model was implemented into the finite element method code. The finite element analysis was applied to simulating die compaction of pure magnesium powders in order to investigate the density and effective strain distributions at room temperature.

Mg-Zn-RE alloys had a novel lond period stacking ordered (LPO) structure. Their rapidly solidified powder metallurgy (RS P/M) alloys exhibited a combination of high strength and god ductility (tensile yield strength above 550 MPa and elongation above 5%). The LPO Mg-Zn-RE RS P/M alloys had high elevated temperature strength (tensile yield strength above 380 MPa at 473 K) and exhibited a high-strain-rate superplasticity at higher temperatures. In Japan, a national project for developing high strength LPO Mg-Zn-RE RS P/M alloys has started at 2003 for 5 years, which is founded by the Ministry of Economy, Trade and Industry (METI) of Japan. In the national project, project targets in materials performances have been achieved. The developed LPO Mg-Zn-RE RS P/M alloys exhibited higher tensile yield strength, fatigue strength and corrosion resistance than high strength aluminum alloys of extra-super-duralumin (7075-T6).

Rapidly solidified ribbon-consolidation processing was applied for preparation of high strength bulk Mg-Zn-Gd alloys. Mg alloys have been used in automotive and aerospace industries. Rapid solidification (RS) process is suitable for the development of high strength Mg alloys, because the process realizes grain-refinement, increase in homogeneity, and so on. Recently, several nanocrystalline Mg-Zn-Y alloys with high specific tensile strength and large elongation have been developed by rapidly solidified powder metallurgy (RS P/M) process. Mg-Zn-Y RS P/M alloys are characterized by long period ordered (LPO) structure and sub-micron fine grains. The both additions of rare earth elements and zinc remarkably improved the mechanical properties of RS Mg alloys. Mg-Zn-Gd alloy also forms LPO structure in -Mg matrix coherently, therefore, it is expected that the RS Mg-Zn-Gd alloys have excellent mechanical properties. In this study, we have developed high strength RS Mg-Zn-Gd alloys with LPO structure and nanometer-scale precipitates by RS ribbon-consolidation processing. and and bulk alloys exhibited high tensile yield strength (470 MPa and 525 MPa and 566 MPa) and large elongation (5.5% and 2.8% and 2.4%).

Fabrication of bulk alloy has been performed through the consolidation of rapidly solidified ribbons. The bulk alloy exhibited excellent mechanical properties, high tensile yield strength of 530 MPa, and large elongation of 3 %. Microstructure of the alloy was characterized by equiaxed fine grains that consist of -Mg, long period ordered (LPO) structure phase, and -type cubic compound. The strengthening of the alloys may be due to fine grains with LPO structure phase and -type compound.

In order to investigate of the Influence of Mg2+, Ca2+ on α-linolenic acid converted into the eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) forming in plasma lipid and in liver microsomes of rabbit, the animals were fed on the perila oil rich α-linolenic acid or sardine oil rich EPA and DBA diet for 4 weeks were examined. In plasma, liver lipid, Mg2+ was influenced on arachidonic acid(AA), EPA, DHA formative from α-linolenic acid in perilla oil, but stearic acid was increased, Ca2+ was Influenced on stearic acid increased and DHA was decreased. In phospholipid, Mg2+, Ca2+ was influenced on stearic acid increased and DHA was decreased in perilla oil.