• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.63-70
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• 1991

Aluminium alloy castings, which can be not only manufactured in larger geometrically complex shapes, but also show good mechanical properties in addition to light weight, have kept their potential use as structures in the field of automotives, industrial machines and aircrafts. The variations of eutectic Si size a great effect on the elongation, impact value, fracture toughness and fatigue crack propagation rate without changes in the tensile strength or yield strength. The cooling curves with the solidification rate between $1.4^{\circ}C\;/min$ and $19.1^{\circ}C\;/min$ were obtained. With the increase of solidification rate, DAS, eutectic Si size and grain size were all decreased, which enhanced the mechanical properties. The tensile strength and yield strength were the most greatly influenced by DAS, and the elongation and impact value by eutectic Si size.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.61-62
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• 2014

To evaluate anti-corrosion performance of high-frequency arc metal spray film in accordance with metal type and epoxy sealing coat application status, electrochemical impedance spectroscopy(EIS) method was conducted in this study. As a result, in case of applying Al-Mg alloy metal spray film, it showed the best polarization resistance. In case of applying epoxy sealing coat, it showed increased polarization resistance of arc metal spray film. Through this experiment, it is judged that Al-Mg alloy arc metal spray film with epoxy sealing coat can increase the biggest anti-corrosion performance of high-frequency arc metal spray film on steel.

• Corrosion Science and Technology
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• v.9 no.2
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• pp.74-80
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• 2010

For the purpose of applying a hot-dip Zn-6mass%Al-3mass%Mg alloy coated steel sheet (ZAM) to automotive body materials, a laboratory study of the general properties required for inner and outer panels of automotive bodies was performed. Even with only light coating weight, ZAM showed an excellent corrosion resistance in terms of both cosmetic and perforation corrosion compared to the currently used materials for automotive bodies, GI70 and GA45. In our study, it was confirmed that ZAM exhibits as good as or better properties than GI70 in terms of spot weldability and press formability. Furthermore, since the same corrosion resistance can be achieved with less coating weight by applying ZAM, laser weldability is better than GI and GA.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.448-453
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• 2011

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped ${\beta}$" phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

• Korean Journal of Metals and Materials
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• v.49 no.9
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• pp.686-691
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• 2011

To develop creep resistant die-cast Mg alloys, various alloying elements, including Ca, Ce, and Sr, were added to a Mg-Al alloy. The AXE710 alloy was produced on a 320 ton high-pressure die casting machine. The microstructure and creep properties of the alloy were examined. The creep behavior was investigated at $150^{\circ}C$ for stresses ranging from 50 to 100 MPa. The stress exponent was derived from the relationship between normalized secondary creep rates and compensated effective stresses. It was found to be 4.9, indicating that the dislocation climb is a dominant creep mechanism.

• Journal of Korea Foundry Society
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• v.21 no.4
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• pp.246-252
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• 2001

Variation in the microstructure of Mg-5%Al semi-solid slurry during isothermal heating was investigated in relation to initial microstructure, holding time, and holding temperature. Specimens with three different initial microstructures were isothermally heated. Dendritic structure in as-cast ingot was decomposed into solid globules in the semi-solid slurry during isothermal holding, while in the recrystallized specimens prepared by extrusion or rolling the size of solid particles was continuously increased during the heating. Effects of mold temperature and liquid fraction of slurry on the mold filling ability were also studied. Very thin section (0.4 mm) could be successfully filled up to 50 mm by 60% liquid slurry when the mold was heated to $600^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.33-40
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• 1994

알루미늄 코팅막은 부식환경으로부터 강판을 보호하는 데에 자주 사용된다. 그러나 이 코팅막은 때때로 사용조건에 따라 제한을 받는다. 아무리 강판상에 치밀한 양질막을 코팅시켰다 할지라도, 사용중 이 피막이 손상을 받아서 강판이 노출되는 경우는 강판과의 갈바닉(Galvanic)작용으로 급격한 부식을 일으킨다. 본 연구는 내식성 개선을 목적으로 해서, 고밀착성의 코팅막을 제공하는 비평형프라즈마 프로세스인 이온프레이팅법에 의해 냉간압연강판상에 Al-Mg합금 코팅막을 제작했다. 제작된 막들은 우선, EMPA측정에 의해 원소조성분석을 한 후, 상구조분석 및 표.단면의 몰포로지(Molphology)를 X선 회절 및 주사형 전자현미경(SEM)에 의해 관찰했다. 또한, 이들막은 탈기시킨 3%NaCl용액중 양극분극 측정을 통해서 내식특성에 대한 평가를 행했다. 이들의 결과에 의하면, 알루미늄과 마그네슘의 조성비에 따라 주상, 미결정 및 아몰포스(Amorphous)조직을 보이는 금속간화합물이나 고용체의 Al-Mg박막이 나타났다. 이들 Al-Mg합금 코팅막은 강판과의 갈바닉 부식작용에 대한 방지 및 부동태 피막의 형성을 촉진하는 등의 좋은 내식성을 나타냈다.

• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.419-425
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• 1997

용탕단조방법에 의해 제조된 Mg-6Al-xZn(x=0, 1, 2)합금의 기계적 성질에 미치는 시효열처리의 영향을 조사한결과 아래와 같은 결론을 얻었다. (1) 주조조직을 관찰한 결과 미세한 수지상조직을 나타냈으며 초정${\alpha}$, 과포화 ${\alpha}$, ${\beta}$상 등 세가지 상으로 구성되어 있었다. (2) Mg-6Al-xZn합금은 시효경화성을 나타내었으며 Zn의 첨가량이 증가할수록 전시효구간에서 경도값이 높게 나타났다. (3) 시효조직을 관찰한 결과 $200^{\circ}C$의 시효시에는 불연속 석출물이 대부분 차지했으나 $240^{\circ}C$의 시효온도에서는 수지상 경계에서 시작되는 미세분산된 연속석출물이 대부분 이었다. (4) $240^{\circ}C$에서 시효열처리 한 시편은 연속석출물이 석출됨으로서 $200^{\circ}C$에서의 시효열처리된 시편에 비하여 과시효되는 경향이 작았다. (5) T6열처리 후 인장시험 결과 Zn 첨가량에 따라 강도가 증가하였는데 Mg-6Al-2Zn합금의 경우 인장강도는 248.4 MPa을 나타내었으며 Zn양에 따른 연신율의 감소는 나타나지 않았다.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.2
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• pp.77-87
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• 1994

Roles of fundamental and additional hardening precipitates on the changes of mechanical properties and electrical resistivity during precipitation decomposition in binary Al-Li, ternaty Al-Li-Cu and multi-Li-Cu-Mg-Zr alloys have been investigated by the detailed measurement of electrical resistivity, hardness and tensile strength and the observation of transmission electron micrographs. Peek hardness and tensile strength in multi-component Al-Li-Cu-Mg-Zr Alloy had higher than that of the other alloys and the results of measurement of hardness, strength and electrical resistivity in each alloys aged at 90 and $190^{\circ}C$, precipitation behaviors and mechanical properties in binary, ternary and multi-component Al-Li alloys were contributed to the ${\delta}^{\prime}$ precursory phase of ${\delta}^{\prime}$, $T_1$, G.P.B. zone and S' phases, repectively.

• Progress in Superconductivity
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• v.9 no.1
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• pp.85-90
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• 2007

Lanthanum aluminate($LaAlO_3$) film has been prepared on single crystal and metal substrates by dip coating method. Lanthanum acetate and aluminum were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate in acetate glacial acetic acid solution after being refluxed. Coating solution was obtained by diluting the gel with methanol and 2-methoxyethanol to adjust the total cation concentration to 0.67 M. Precursor coated film was prepared by dip-coating with a speed of 25 mm/min on various substrates such as $LaAlO_3$ (001), MgO(001), $SrTiO_3$(001) single crystal, LMO/MgO/Ni-alloy. Thin films have been obtained by heat treating the precursor film at various temperatures from $600^{\circ}C{\sim}900^{\circ}C$ and various heating rate from $0.83^{\circ}C/min{\sim}1.25^{\circ}C/min$ under $Ar/O_2$ mixture containing 1000ppm oxygen. The films have been characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). XRD analysis for the prepared film showed that $LaAlO_3$ thin films with a preferred orientation of (100) plane parallel to substrate surface were obtained at $800^{\circ}C(1.11\;^{\circ}C/min)$ on LMO/MgO/Ni-alloy substrate, but the intensity decreased with the increase of heat treatment temperature.