• 한국주조공학회지
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• 제41권1호
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• pp.3-10
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• 2021

알루미늄 합금과 주철의 복합주조 공정 중에는 주철로부터 철 성분이 용해되어 알루미늄 용탕에 혼입될 수 있으므로 다양한 Fe함유 금속간 화합물이 형성되며, 이로 인해 알루미늄 합금의 인장 특성이 크게 저하 될 수 있다. 반면 불순물로 첨가되는 Fe와 는 달리 Cu의 경우 알루미늄 합금의 기계적 물성을 향상시키기 위해 첨가되는 합금원소이다. 본 연구에서는 Fe와 Cu의 첨가로 인한 알루미늄 합금의 미세조직 및 인장특성의 변화를 조사하였다. 첨가된 Fe 함량이 1% 이상일 경우 조대한 Al₅FeSi 상과 같은 Fe 함유 화합물들이 다량 형성되어 인장 특성이 현저히 감소하는 것으로 나타났다. Cu가 첨가 된 알루미늄 합금의 경우 Al2Cu 상이 추가로 형성되었으며, 인장 강도가 뚜렷하게 향상되는 결과를 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.173-178
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• 2001

The materials processing factors such as remelting and casting, heat treatment and microstructure, sheet rolling and can body forming in the aluminum can-to-can recycling procedure have been investigated. Aluminum used beverage can(UBC) was remelted together with virgin aluminum. The ceramic filter was used during casting to remove large impurities. As-cast microstructure was composed of large intermetallic compound (mainly $\beta$ -phase) distributed in the aluminum matrix. By heat treatment, $\beta$ -phase was transformed to $\alpha$ -phase which was also formed from $Mg_2$Si particles. The heat treated ingots were hot-rolled at 48$0^{\circ}C$ and cold-rolled to thin sheets. Can making from this thin sheets was successful and earing was measured after can making. There was a critical cold reduction rate for minimum earing. Some cracks were initiated from the impurity particles which was not removed during filtering.

• 열처리공학회지
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• 제12권1호
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• pp.1-8
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• 1999

This study has investigated the effect of aging treatment on the microstructure and mechanical properties of Mg-6Al-xZn(x = 1.5, 2.5) alloys fabricated by the squeeze casting process. The microstructures of as-squeeze cast were composed of pro-eutectic ${\alpha}$, super saturated ${\alpha}$ and ${\beta}(Mg_{17}Al_{12})$ compound. Aged at both $200^{\circ}C$ and $240^{\circ}C$, Mg-6Al-xZn alloys showed the peak hardness due to the formation of ${\beta}(Mg_{17}Al_{12})$ precipitates. The discontinuous precipitates of the lamella type are predominant at $200^{\circ}C$ aging treatment, while the finely dispersed continuous precipitates were dominant at $240^{\circ}C$ aging treatment. Mg-6Al-xZn alloys fabricated by the squeeze casting process had the better combination of tensile strength and elongation compared to the conventionally cast alloys. As zinc contents increased, the tensile strength was increased by the solid solution strengthening effect of zinc.

• 한국주조공학회지
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• 제25권2호
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• pp.80-87
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• 2005

The microstructure and mechanical property of the Ni and Ni-Cr porous metal reinforced AC4C matrix composites fabricated by squeeze casting were investigated. In this study Ni, Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for composite materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, $750^{\circ}C$ melt temperature and minimum 25MPa squeezing pressure are needed to produce sound composite materials. The observation of interfacial reaction zone at various heat treatment condition shows that atsolutionizing temperature of above $520^{\circ}C$, the interfacial reaction zone increases proportionally with heat treatment time and the reaction products formed by interfacial reactions are mainly composed by $Al_{3}Ni$ and $Al_{3}Ni_{2}$ phases.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.109-115
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• 2000

In the present study, (10%$Al_2O_3$+5%Si)/AZ91 Mg hybrid composite was fabricated using the squeeze casting method. During squeeze casting, molten Mg was infiltrated into the preform of 10%$Al_2O_3$+5%Si and reaction product of $Mg_2Si$ intermetallic compound was formed by the reaction between molten Mg and Si powder. Microstructure has been observed and mechanical properties were evaluated for the reaction squeeze cast (RSC) hybrid composite. It was found that Si powder totally reacted with molten Mg to form $Mg_2Si$. Reinforcement ($Al_2O_3$) and the reaction product ($Mg_2Si$) are fairly uniformly distributed in Mg matrix for the squeeze cast hybrid composite. Mechanical properties were improved with hybridization of reinforcements, namely higher hardness and enhanced wear resistance comparing squeeze cast (15%$Al_2O_3$)/AZ91 Mg composite.

• 열처리공학회지
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• 제35권3호
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• pp.150-158
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• 2022

The effects of scandium addition on the Al-6Si-2Cu Alloy were investigated. The Al-6Si-2Cu-Sc alloy was prepared by gravity die casting process. In this study, scandium was added at 0.2 wt%, 0.4 wt%, 0.8 wt%, and 1.0 wt%. The microstructure of Al-6Si-2Cu-Sc alloy was investigated using Optical Microscope, Field Emission Scanning Electron Microscope, Electron Back Scatter Diffraction, and Transmission Electron microscope. The microstructure of Al-6Si-2Cu alloy with scandium added changed from dendrite structure to equiaxed crystal structure in specimens of 0.4 wt% Sc or more, and coarse needle-shape eutectic Si and β-Al₅FeSi phases were segmented and refined. The nanosized Al₃Sc intermetallic compound was observed to be uniformly distributed in the modified Al matrix.

• 소성∙가공
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• 제28권3호
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• pp.123-129
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• 2019

Hypereutectic Al-Si alloys have been widely utilized for wear-resistant components in the automotive industry. In order to expand the application of Hypereutectic Al-Si alloys, the addition of alloying elements forming a stable precipitate at high temperature is required. Thermally stable inter metallic compounds can be formed through the addition of transition elements such as Fe, Ni to Al alloys. However, the amount of transition element to be added to Al alloys is limited due to their low solid solubility. Also, hypereutectic Al-Si-Fe alloys form coarse primary Si phases and needle-shaped intermetallic compounds during solidification in the general casting processes. In this study, the effects of the destruction of Intermetallic compound and Si phase are investigated via hot extrusion. Both the microstructure and mechanical properties are discussed under different extrusion conditions.

• Advances in materials Research
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• 제5권1호
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• pp.55-66
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• 2016

This paper describes a study on the effects of $Mg_2Si_{(p)}$ addition on the microstructure, porosity, and mechanical properties namely hardness and tensile properties of AA332 composite. Each composite respectively contains 5, 10, 15, and 20 wt% reinforcement particles developed by a stir-casting. The molten composite was stirred at 600 rpm and melted at $900^{\circ}C{\pm}5^{\circ}C$. The $Mg_2Si$ particles were wrapped in an aluminum foil to keep them from burning when melting. The findings revealed that the microstructure of $Mg_2Si_{(p)}/AA332$ consists of ${\alpha}$-Al, binary eutectic ($Al+Mg_2Si$), $Mg_2Si$ particles, and intermetallic compound. The intermetallic compound was identified as Fe-rich and Cu-rich, formed as polygonal or blocky, Chinese script, needle-like, and polyhendrons or "skeleton like". The porosity of $Mg_2Si_{(p)}/AA332$ composite increased from 8-10% and the density decreased from 9-12% from as-cast. Mechanical properties such as hardness increased for over 42% from as-cast and the highest UTS, elongation, and maximum Q.I were achieved in the sample of 10% $Mg_2Si$. The study concludes that combined with AA332, the amount of 10 wt% of$Mg_2Si$ is a suitable reinforcement quantity with the combination ofAA332.

• 한국주조공학회지
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• 제19권5호
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• pp.403-409
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• 1999

Mg-Zn-Zr ternary alloys containing 6wt% Zn and (0, 0.4, 0.6)wt% Zr, which is added for grain refinement, can be cast into complex shape by squeeze casting. The influence of Zn and Zr as additional elements on microstructure and mechanical characteristics is investigated by OM, SEM, WDX, XRD and microvickers hardness measurement. The microstructure of Mg-Zn-Zr alloys consists of primary ${\alpha}-Mg$ and MgZn eutectic compound between dendrites. The grain size is decreased from $136{\mu}m$ to $97\;{\mu}m$ by Zr addition, resulting in that the hardness is increased from 42Hv to 59Hv. Furthermore, the grain size is changed to $83{\beta}$ and the hardness is increased to 65Hv by additional infiltration pressure. These results indicate that the Zr addition and additional infiltration pressure are effective for grain refinement acting as an important factor to increase the hardness. The increment in hardness by the Zr addition is slightly larger than that by the additional infiltration pressure.

• 한국주조공학회지
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• 제20권1호
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• pp.13-20
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• 2000

In the present study,($10%Al_2O_3+5%Si$)/AZ91 Mg hybrid composite was fabricated using the squeeze casting method. During squeeze casting, Molten Mg was infiltrated into the preform of $10%Al_2O_3+5%Si$ and reaction product of $Mg_2Si$ intermetallic compound was formed by the reaction between molten Mg and Si Powder. Microstructure has been observed and mechanical properties were evaluated for the reaction squeeze cast(RSC) hybrid composite. It was found that Si powder totally reacted with molten Mg to form $Mg_2Si$. Reinforcement($Al_2O_3$) and the reaction product ($Mg_2Si$) are fairly uniformly distributed in Mg Matrix for the squeeze cast hybrid composite. Mechanical Properties were improved with hybridization of reinforcements, namely higher hardness and enhanced wear resistance comparing squeeze cast($15%Al_2O_3$)/AZ91 Mg composite.