• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.300-306
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• 2000

The objective of this work was to investigate the effects of SiC particle size(50, 100 ${\mu}m$) and additional elements such as Si, Cu and Ti on aging behavior in Al-5Mg-X(Si,Cu,Ti)/SiCp composites fabricated by pressureless infiltration method using hardness and wear test, scanning electron microscopy(SEM) and differential scanning calorimetry(DSC). The peak aging time in Al-5Mg-X(Si, Cu, Ti)/SiCp(50, 100 ${\mu}m$) composites is shorter than Al-5Mg-0.3Si alloy.The peak aging time of 50 ${\mu}m$ SiC particle reinforced Al-5Mg-X(Si,Cu,Ti) composites is shorter than those of 100 ${\mu}m$ SiC particle reinforced of Al-5Mg-X(Si,Cu,Ti) composites. The Al-5Mg-0.3Si-0.1Cu-0.1Ti/SiCp(50 ${\mu}m$) composites aged at $180^{\circ}C$ has higher hardness and better wear resistance than any other aged composite.The aging effect is promoted by the addition of Si and Cu in Al-5Mg/SiCp composites, so the wear resistance of Al-5Mg/SiCp composites with Si and Cu elements is enhanced by the aging treatment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.307-310
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• 2005

Ageing behavior of the Al-Mg-Si alloy was modeled for the use of optimization of Al forging product. Typical precipitates of Al-Mg-Si alloy are a wide variety of metastable phases (e.g. GP zones, $\beta',\beta'$). These rod shaped particles take a role to hinder the dislocation movement. The precipitation sequence in Al-Mg-Si alloys is quite complex and the strength of precipitate particles differs with the ageing condition. In the present study, the ageing behavior of Al-Mg-Si alloy was investigated by using an industrial grade Al 6061 alloy forged product, which was a perform for an Al impeller for turbo charger. The precipitate hardening models by Esmaeili's approach were used for the analysis of ageing behavior.

• Journal of Korea Foundry Society
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• v.32 no.6
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• pp.269-275
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• 2012

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 Al. The growth of columnar grains in pure Al occurred from the macro-interface. The tensile strength, 0.2% proof stress and bending strength of the hybrid aluminum alloy were almost similar to those of pure Al, and the elongation was much higher than the Al-Mg-Si alloy. The fracture of the hybrid alloy took place in pure Al side, indicating that the macro-interface was well bonded and the mechanical behavior strongly depends on the limited deformation in pure Al side.

• International Journal of Korean Welding Society
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• v.2 no.2
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• pp.42-46
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• 2002

The solidification cracking susceptibilities of Al-Mg-Si alloy laser welds were assessed using the self-restraint tapered specimen crack test. The cracking susceptibility of 6061 and 6082 Al-Mg-Si alloy laser welds was substantially reduced when the filler wire containing high Si such as Al-12 wt.% Si (4047A) was used. The amount of eutectic was observed to affect the solidification cracking of Al-Mg-Si alloy laser welds. Abundant eutectic seems to heal the cracking and reduces the cracking susceptibility, while an initial increase in eutectic liquid leads to the increased cracking tendency.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.628-634
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• 2016

The cold rolling workability and mechanical properties of two new alloys, designed and cast Al-5.5Mg-2.9Si and Al-7Mg-0.9Zn alloys, were investigated in detail. The two alloy sheets of 4 mm thickness, 30 mm width and 100 mm length were reduced to a thickness of 1 mm by multi-pass rolling at ambient temperature. The rolling workability was better for the Al-7Mg-0.9Zn alloy than for the Al-5.5Mg-2.9Si alloy; in case of the former alloy, edge cracks began to occur at 50% rolling reduction, and their number and length increased with rolling reduction; however, in the latter alloy, the sheets did not have any cracks even at higher rolling reduction. The mechanical properties of tensile strength and elongation were also better in the Al-7Mg-0.9Zn alloy than in Al-5.5Mg-2.9Si alloy. Work hardening ability after cold rolling was also higher in the Al-7Mg-0.9Zn alloy than in the Al-5.5Mg-2.9Si alloy. At the same time, the texture development was very similar for both alloys; typical rolling texture developed in both alloys. These differences in the two alloys can primarily be explained by the existence of precipitates of $Mg_2Si$. It is concluded that the Al-7Mg-0.9Zn alloy is better than the Al-5.5Mg-2.9Si alloy in terms of mechanical properties.

• Journal of Korea Foundry Society
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• v.33 no.2
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• pp.55-62
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• 2013

Effect of Fe and Mn contents on the castability of Al-4wt%Mg-0.9wt%Si system alloy has been studied. According to the analysis of cooling curve for Al-4wt%Mg-0.9wt%Si-0.3wt%Fe-0.3/0.5wt%Mn alloy, ${\alpha}-Al_{15}(Fe,Mn)_3Si_2$ and ${\beta}-Al_5FeSi$ phases crystallized above eutectic temperature of $Mg_2Si$. Therefore, these phases affected both the fluidity and shrinkage behaviors of the alloy during solidification. As Fe and Mn contents of Al-4wt%Mg-0.9wt%Si system alloy increased from 0.1 wt% to 0.4 wt% and from 0.3 wt% to 0.5 wt% respectively, the fluidity of the alloy decreased by 26% and 33%. When Fe content of the alloy increased from 0.1 wt% to 0.4 wt%, 23% decrease of macro shrinkage and 19% increase of micro shrinkage appeared. Similarly, Mn content of the alloy increased from 0.3 wt% to 0.5 wt%, 11% decrease of macro shrinkage and 14% increase of micro shrinkage appeared. Judging from the castability of the alloy, Al-4wt%Mg-0.9wt%Si alloy with low content of Fe and Mn, 0.1 wt% Fe and 0.3 wt% Mn, is recommendable.

• Journal of Korea Foundry Society
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• v.31 no.1
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• pp.18-25
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• 2011

Effect of Fe and Mn contents on the tensile properties has been studied in Al-9wt%Si-0.3wt%Mg alloy. As Fe content of Al-9wt%Si-0.3wt%Mg-0.5wt%Mn alloy increased from 0.15wt% to 0.45wt%, tensile strength of as-cast alloy decreased from 192 MPa to 174 MPa, and elongation of the alloy also decreased from 4.8% to 4.2%. Decrease of these properties can be explained as the formation of plate shape, ${\beta}-Al_5FeSi$ phase with high Fe/Mn ratio of the alloy. However when Mn content of Al-9wt%Si-0.3wt%Mg-0.45wt%Fe alloy increased from 0.3wt% to 0.5wt%, tensile strength of T6 aged alloy increased from 265 MPa to 275 MPa, and elongation of the alloy increased from 2.3% to 3.6%. These improvements attribute to chinese script, ${\alpha}-Al_{15}(Mn,Fe)_3Si_2$ phase shape-modified from ${\beta}-Al_5FeSi$ phase with low Fe/Mn ratio of the alloy.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.74-81
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• 2001

The infiltration behavior of molten Al-alloy, microstructures, hardness, and the interfacial reactions of $SiC_p/Al$ composites fabricated by the pressureless infiltration technique were investigated. It was made clear that both the weight fraction of SiC reinforcement and additive Mg content considerably influenced on the infiltration behavior of the molten Al-alloy matrix. Complete infiltration of molten Al-alloy achieved under the conditions that weight fraction of SiC content is more than 30wt%, and additive Mg content is more than 9wt%. Interfacial region of Al-alloy matrix and SiC reinforcement phase, $Mg_2Si$ was formed by the reaction between Mg and SiC. Another reaction product AlN was also formed by the reaction between Al-alloy matrix and gas atmosphere nitrogen.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.48-54
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• 2003

Alumium alloys casting are gaining increased acceptance in the automotive and electronic industeries and squeeze casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Al-7.0Si-0.4Mg (AC4C) alloy fabricated by squeeze casting process for development of Fuel system Parts (Fuel rail). The microstructure of squeeze casted specimen were composed of eutectic structure Alumimim solid solution and $Mg_2$Si precipitates. The tensile strength of as-solid solution treatment Al-7.0Si-0.4Mg ahoy revealed 298.5MPa. It was found that Al-7.0Si-0.4Mg alloy have good corrosion resistance in electrochemical polarization test.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.14-19
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• 2017

The corrosion characteristics of Al-Si-Mg alloy were investigated in $O_2$ and $H_2S/H_2$ environments at high temperature. The weight gain and the reaction rate constant of the Al-Si-Mg alloy were measured in the oxygen and hydrogen sulfide environments at 773K. The weight gain of Al-Si-Mg alloy was showed parabolic increase in the oxygen and hydrogen sulfide environments. The reaction rate constants were confirmed to be $1.45{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the oxygen environment and $6.19{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the hydrogen sulfide environment respectively. As a result of XPS analysis on the specimen surface, $Al_2O_3$ and MgO compounds were detected in oxygen environment and $Al_2(SO_4)_3$ sulfate was detected in the hydrogen sulfide environment. Corrosion rate of Al-Si-Mg alloy was about 4.3 times faster in hydrogen sulfide environment than oxygen environment.