• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.57-62
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• 1983

The galvanic anodes have three kinds of Zn alloy anode, Al alloy anode and Mg alloy anode, which are widely used in cathodic protection for all metal structures in water or under ground. This paper to be used for designing of the grounding cell has reached the following conclusion as the results of an experimental study on the characteristics of such galvanic anodes for corrosion protection of pipings: 1) Zn alloy anode was the best when the specific resistance of the environment was bellow 1000 $\Omega$.cm, and when above 1000 $\Omega$.cm, Mg alloy anode to be used for designing of the grounding cell was the best. 2) Al alloy anode was better than Mg alloy anode for grounding cell when the specific resistance was bellow 500 $\Omega$.cm, but the Al alloy anode in all the environments reduced the characteristics of galvanic anode to the lower grade than those of Zn alloy anode. 3) Each impressed voltage (E) of the anodes at which drainage current density ($\rho$) begins rapidly increasing is quantitatively presented as follows: \circled1 E sub(Zn)=log (4.9465/$\rho$super(0.0639))+11$\times$10 super(-6)$\rho$super(0.8923i) \circled2 E sub(Al)=log (4.9306/$\rho$super(0.0525))+13$\times$10 super(-6)$\rho$super(0.9314i) \circled3 E sub(Mg)= log (3.7086/$\rho$super(0.0988))+181$\times$10 super(-6)$\rho$super(0.5406i) 4) The empirical equations between the drainage current density (i) and impressed environment are modeled as the following type. logi=g+root(n.E+r)(g,n,r; constants)

• Transactions of Materials Processing
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• v.26 no.5
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• pp.306-313
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• 2017

This study investigated the microstructure, tensile strength, and high cycle fatigue properties of ADC12 aluminum alloys with different $Mg+Al_2Ca$ contents manufactured using die casting process. Microstructural observation identified the presence of ${\alpha}-Al$, eutectic Si, $Al_2Cu$, and Fe-intermetallic phases. The increase of $Mg+Al_2Ca$ content resulted in finer pore size and decreased pore distribution. Room temperature tensile strength tests were conducted at strain rate of $1{\times}10^{-3}/sec$. For 0.6%Mg ADC12, measured UTS, YS, and El were 305.2MPa, 157.0MPa, and 2.7%, respectively. For 0.8%Mg ADC12, measured UTS, YS, and El were 311.2 MPa, 159.4 MPa, and 2.4%, respectively. Therefore, 0.8% ADC12 alloy had higher strength and slightly decreased elongation compared to 0.6% Mg ADC12. High cycle fatigue tests revealed that 0.6% Mg ADC12 alloy had a fatigue limit of 150 MPa while 0.8% Mg ADC12 had a fatigue limit of 160MPa. It was confirmed that $Mg+Al_2Ca$ added ADC12 alloy achieved finer, spherical eutectic Si particles, and $Al_2Cu$ phases with greater mechanical and fatigue properties since size and distribution of pores and shrinkage cavities decreased as $Mg+Al_2Ca$ content increased.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.166-177
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• 1997

The high strength AlZnMgCu0.5 alloy is a light metal with good age hardenability, and has a high tensile and yielding strength. Therefore, it can be used for structures requiring high speciple strength. Even though high strength AlZnMgCu alloy has good mechanical properties, it has a lot of problems in TIG and MIG welding processes. Since lots of high heat absorption is introduced into the weldment during TIG and MIG processes, the microstructural variation and hot cracks take place in heat affected zone. Therefore, the mechanical properties of high strength AlZnMgCu0.5 alloy can be degraded in weldment and heat affected zone. Welding process utilizing high density heat source such as electron beam should be developed to reduce pore and hot cracking, whichare usually accompanied by MIG and TIG welding processes. In this work, electron beam welding process were used with or without AlMg4.5Mn as filler material to avoid the degradation of mechanical properties. Mechanical and metallurgical characteristics were also studied in electron beam weldment and heat affected zone. Moreover hot cracking mechanism was also investigated.

• Journal of Powder Materials
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• v.4 no.2
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• pp.100-105
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• 1997

In this study the changes of the hardness and microstructures during aging at 120$^{\cire}C$ of an RS-P/M Al-5.6wt%Zn-2.0wt%Mg-1.3wt%Zr-1.0wt%Mn-0.25wt%Cu alloy were studied using a transmission electron microscopy. The hardness increased rapidly at early stage of aging and reached the maximun when the specimen was aged for 24 hr. The many irregular-shaped $Al_4Mn$ and rod-shaped $Al_6Mn$ dispersoids with 0.1-0.4 $\mu$m in length were observed in the as-extruded alloy. The dark particles with 2-3 nm in size were observed in aged specimen for 5hr and those are thought to be G.P.zones or precursor of $\eta'$ precipitates. In aged specimen for 24 hr, the $\eta'$ phases were distributed homogeneously within the matrix and the PFZ with 30-40 nm in width was observed along the grain boundary. With further aging, the width of PFZ increased and $\eta$ phases were also detected within the matrix.

• Journal of Korea Foundry Society
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• v.37 no.4
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• pp.101-107
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• 2017

This study investigated the effect of Pd on the microstructure, tensile and creep properties of Mg-4Al-2Sn (AT42) alloy at a high temperature for transportation-related industrial applications. AT42-xPd (x = 0, 1 and 2 wt. %) alloys were prepared using a permanent mould casting method. The microstructures of the as-cast alloys were characterized by the presence of the intermetallic phases $Mg_{17}Al_{12}$, $Mg_2Sn$ and $Al_4Pd$. The addition of Pd was found to improve the tensile properties of AT42 at room and at elevated temperatures, and to increase the creep resistance at elevated temperatures. A small amount of Pd could markedly improve the tensile properties of AT42 by means of grain-refinement and the dispersion of secondary phase strengthening. Moreover, the thermally stable phase $Al_4Pd$ effectively improves the creep resistance of AT42 due to the strengthened grain boundaries and the suppressed formation of $Mg_{17}Al_{12}$.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.382-387
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• 2004

Nanoindentation technique has been used to measure the mechanical properties of aluminium alloy foam cell walls. Al-Si-Cu-Mg alloy foams of different compositions and different cell morphologies were produced using powder metallurgical method. Cell morphology of the foam was controlled during production by varying foaming time and temperature. Mechanical properties such as hardness and Young's modulus were calculated using two different methods: a continuous stiffness measurement (CSM) and an unloading stiffness measurement (USM) method. Experimental results showed that hardness and Young's modulus of Al-5%(wt.)Si-4%Cu-4%Mg (544 alloy) precursor and foam walls are higher than those of Al-3%Si-2%Cu-2%Mg (322 alloy) precursor and foam walls. It was noticed that mechanical properties of cell wall are different from those of precursor materials.

• Journal of Korea Foundry Society
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• v.31 no.5
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• pp.284-287
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• 2011

Microstructures and tensile properties at ambient and elevated temperatures were studied by substituting RE for Sr in Mg-6%Al-(3-X)%RE-X%Sr alloys (X = 0~3). With increasing Sr content, $Al_4Sr$ phase with lamellar morphology was newly introduced at interdendritic regions, with a gradual extinction of needle-shaped $Al_4RE$. The Mg-6%Al-3%Sr alloy shows dendritic grains and interdendritic eutectic phases containing bulky Mg-Al-Sr and lamellar $Al_4Sr$ with more continuous manner. The substitution of Sr for RE provided higher YS, UTS and creep resistance at $175^{\circ}C$, which indicates that Sr would be more beneficial in tensile properties and creep resistance at elevated temperature than RE for the Mg-Al based casting alloys.

• Journal of Korea Foundry Society
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• v.26 no.6
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• pp.249-257
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• 2006

The effects of alloying element and the condition of heat-treatment on the strength of squeeze-cast Al-3.0 wt%Si alloy were investigated. The strength of the alloy without grain refinement was increased with increase Cu content upto 3.0 wt% and rather decreased beyond that. The tensile strength of the alloy with grain refinement increased with Cu content upto 3.0 wt% and not changed beyond that. The strength of the alloy without grain refinement increased with the Mg content. The tensile strength with grain refinement increased with the Mg content upto 0.50 wt% and then decreased beyond that. The strength of the grain refined alloy increased by individual and simultaneous additions of Cu and Mg and the maximum strength was obtained with Al-3.0 wt%Si-4.5 wt%Cu-0.50 wt%Mg alloy. The optimum heat-treatment condition for this alloy was obtained.

• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.186-191
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• 2014

Double layer films which consisted of aluminum(Al) and magnesium(Mg) have been prepared by e-beam deposition. The structure, alloy phase, and corrosion resistance of the prepared films were investigated before and after heat treatment. The first (bottom) layer fixed with Al, and the thickness ratio between Al and Mg layers has been changed from 1 : 1 to 5 : 1, respectively. Total thickness of Al-Mg film was fixed at $3{\mu}m$. The cold-rolled steel sheet was used as a substrate. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 2, 3 and 10 min. Surface morphology of as-deposited Al-Mg film having Mg top layer showed plate-like structure. The morphology was not changed even after heat treatment. However, cross-sectional morphology of Al-Mg films was drastically changed after heat treatment, especially for the samples heat treated for 10 min. The morphology of as-deposited films showed columnar structure, while featureless structure of the films appeared after heat treatment. The x-ray diffraction data for as-deposited Al-Mg films showed only pure Al and Mg peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ appeared after heat treatment of the films. It is believed that the formation of Al-Mg alloy phase affected the structure change of Al-Mg film. It was found that the corrosion resistance of Al-Mg film was increased after heat treatment.

• Journal of Korea Foundry Society
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• v.33 no.4
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• pp.171-180
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• 2013

The effects of alloying elements on the solidification characteristics, microstructure, thermal conductivity, and tensile strength of Al-Zn-Mg-Fe alloys were investigated for the development of high strength and high thermal conductivity aluminium alloy for die casting. The amounts of Zn and Mg in Al-Zn-Mg-Fe alloys had little effect on the liquidus/solidus temperature, the latent heat for solidification, the energy release for solidification and the fluidity of Al-Zn-Mg-Fe alloys. Thermo-physical modelling of Al-Zn-Mg-Fe alloys by the JMatPro program showed $MgZn_2$, AlCuMgZn and $Al_3Fe$ phases in the microstructure of the alloys. Increased amounts of Mg in Al-Zn-Mg-Fe alloys resulted in phase transformation, such as $MgZn_2{\Rightarrow}MgZn_2+AlCuMgZn{\Rightarrow}AlCuMgZn$ in the microstructure of the alloys. Increased amounts of Zn and Mg in Al-Zn-Mg-Fe alloys resulted in a gradual reduction of the thermal conductivity of the alloys. Increased amounts of Zn and Mg in Al-Zn-Mg-Fe alloys had little effect on the tensile strength of the alloys.