• 한국결정성장학회지
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• 제26권4호
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• pp.155-158
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• 2016

전자소자내의 방열특성은 제품의 신뢰성을 결정하는 우주 중요한 인자중의 하나이다. 본 연구에서는 Al과 graphite 분말을 기계적 합금법(mechanical alloying)을 이용하여 Al/graphite 복합체 분말을 합성하고, 합성된 분말을 열처리한 시편에 대한 물리적 특성을 분석하였다. 열처리가 완료된 Al/graphite 샘플에서 열처리 온도 및 시간이 증가할수록 $Al_4C_3$ 이차상의 비율이 증가함을 확인하였다. 또한 Al/graphite 샘플의 열전도도는 순수 Al 분말 샘플에 비해 현저히 낮았으나, 열처리 온도와 시간에 비례하여 증가하는 것을 확인하였다.

• 한국표면공학회지
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• 제37권2호
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• pp.128-136
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• 2004

Effects of alloying elements on the surface characteristics of Fe-38Al intermetallic compounds were investigated using potentiostat. The specimens were casted by the vacuum arc melting. The subsequent homogenization and the stabilization led to the homogeneous DO$_3$ structure of the specimen. After the corrosion tests, the surface of the tested specimen was observed by the optical microscopy and scanning electron microscopy(SEM). For Fe-38 at.% Al intermetallic compound, the addition of Cr and Mo proved to be beneficial in decreasing the grain boundary attack by decreasing the active current density. Addition of Band Nb resulted in a higher active current density and also a higher passive current density. These results indicated the role of Cr and Mo in improving the pitting corrosion resistance of Fe-38 at.%Al intermetallic compound. Band Nb addition to Fe-38 at.%Al accelerated the granular corrosion. Fe-38 at.%Al containing Cr and Mo showed remarkably improved pitting corrosion resistance in comparison with Band Nb addition to Fe-38 at. %Al.

• 열처리공학회지
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• 제14권2호
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• pp.96-102
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• 2001

$Al_2O_3$-copper alloy has been successfully made by gas atomization, mechanical alloying and hot pressing. In order to investigate microstructure and phase, it has been studied by using scanning electron microscope, transmission electron microscope and X-ray diffractometor. Mechanical properties have been examined using hardness tester and compressive tester according to annealing temperature. Although comparatively large Cu-Al powders are milled, the reaction between Cu-Al and $Cu_2O$ occurs and very fine $Al_2O_3$ particles in the matrix particles (5-10nm) are obtained. Compressive strength of this alloy is more than that of GlidCop Al60.

• 대한금속재료학회지
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• 제49권11호
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• pp.839-844
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• 2011

We examined the effects of alloying elements such as Fe, Ga, In, Sn, Mg, and Mn on the electrochemical characteristics of Al-based alloys for Al-air batteries by potentiodynamic polarization tests and electrochemical impedance spectroscopy. The corrosion potential of an Al anode was lowered by the addition of Ga and Sn, resulting in an increase in the cell voltage compared with a pure Al electrode. Fe was not beneficial to improve the electrochemical properties of the Al anode in that it caused a decrease in the cell voltage and reduced corrosion rate slightly. In, Mn, Sn, and Mg decreased the corrosion rate of the Al alloys, while Ga enhanced corrosion significantly and accelerated consumption of the anode.

• 열처리공학회지
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• 제9권3호
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• pp.177-186
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• 1996

Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN or TiC surface-alloyed layer with high hardness on the substrate by injecting reaction gas($N_2$ or $CH_4$). Laser surface alloying by means of process control is in many applications essential in order to obtain predictable hardening layer. This research has been investigated the effect of such parameters on TiN and TiC gas alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum surface hardness of TiN layer was obtained 1750Hv on the conditions of 0.8kW laser power, 0.8m/min scanning speed and 100% $N_2$ atmosphere. However, the maximum hardness of TiC formation layer after laser treatment was about 630Hv. As scanning speed was increased, the hardness and depth of these layers were decreased at constant laser power.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1996년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.31-31
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• 1996

• 열처리공학회지
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• 제7권1호
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• pp.3-10
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• 1994

The structure and mechanical properties of the extruded specimens were investigated in rapid solidified Al-(1, 3, 5) Cr alloys after mechanical alloying. Finer lamellar microstructure could no longer be resolved in the bars obtained by extrusion of the spherical particles after 200 min. of processing time. The structure of extruded bars are highly depended on the processing time of splats. The isothermal annealing of the extruded bars showed that all the alloys had good thermal stability up to $400^{\circ}C$ and did not show the recrystallization phenomena. Severe working of Al-(1, 3, 5) Cr splats produced a very fine grain size and substructural strengthening (high dislocation density and fine grain size). Effects of mechanical alloying on the thermal stability of the extruded bars Al-(1, 3, 5) Cr alloys decreases, with increasing Cr content. But the ultimate tensile Strength in the extruded bars increases with increasing Cr content.

• 한국재료학회지
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• 제11권5호
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• pp.393-397
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• 2001

고온구조용 재료로의 사용이 기대되는 $Al_3$Ti금속간 화합물의 연성 향상을 위한 목적으로 기계적 합금화를 통한 cubic Ll$_2$구조의 생성거동과 Mn의 첨가 영향을 조사하였다. Al-8Mn-25Ti조성에서 20시간의 기계적 합금화를 통해 약 1.0nm 사이즈의 grain을 갖는 nanocrystalline cubic Ll$_2$Al$_3$Ti 금속간 화합물이 제조되었다. Mn이 첨가된 3원계 cubic Ll$_2$Al$_3$Ti 금속간 화합물은 2원계 cubic Ll$_2$Al$_3$Ti 금속간 화합물에서 보이는 Ll$_2$구조에서 D0$_{23}$구조나 D0$_{22}$구조로의 상변태가 발생하지 않았으며 Mn의 첨가로 인해 Ll$_2$구조는 120$0^{\circ}C$가지 안정함을 보였다.

• 한국분말재료학회지
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• 제6권4호
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• pp.277-285
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• 1999

Mechanical properties of nanocrystalline Al-5at.%Ti alloy were investigated through high temperature compression test. Al-5at.%Ti nanocrystalline metal powders, which had finer and more equiaxed shape than those produced at room temperature, were produced by mechanical alloying at low temperature. The powders were successfully consolidated to 99fo of theoretical density by vacuum hot pressing. XRD and TEM analysis revealed that $Al_3Ti$ intermetallic compounds formed inside powders and pure Al region with coarse grains formed between powders, especially at triple junction. Mechanical properties in terms of hardness and strength were improved by grain size refinement, but ductility decreased presumably due to the formation of the weak interfaces between Al pool and powders.

• 한국재료학회지
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• 제13권9호
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• pp.561-566
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• 2003

Mechanical alloying(MA) process using elemental powders followed by hot pressing has been applied to some intermetallic alloy system containing ferromagnetic elements, such as NiAl and $FeSi_2$. A modified thermogravimetric analysis (TGA) technique was used to investigate the degree of alloying in milled powders and hot consolidated specimens as well as heat-treated bulk specimens. It is shown that the measurement of Curie temperatures in MA intermetallic powders and consolidated specimens containing ferromagnetic components, when determined as a function of milling and heat treatment parameters, can give some insight into the progress and mechanism of alloying.