• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.234-240
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• 2001

The diffusion barrier properties of TiN by using Cu(Mg) alloy film have been investigated. Cu(Mg) alloy film was deposited on air-exposed TiN film. Upon annealing, interfacial MgO of 100 $\AA$ has been formed due to the reaction of Mg with oxygen existed on the surface of TiN. Combined MgO/TiN structure prevented the interdiffusion of Cu and Si up to $800^{\circ}C$. To improve the adhesion of Cu(Mg) alloy film to the TiN, TiN layer was treated by $O_2$ plasma, followed by vacuum annealing at $300^{\circ}C$. It was found that increased oxygen on the surface of TiN film by plasma treatment enhanced segregation of Mg toward the interface, resulting in the formation of dense MgO layer. Improved adhesion characteristics have been formed through this treatment. However, increased power of $O_2$ plasma led to the formation of TiO$_2$ and decreased the Mg content to be segregated to the interface, resulting in the decrease in adhesion property. In addition, the deposition of 50 ${\AA}$ Si on the TiN enhanced the adhesion of Cu(Mg) alloy to TiN without deteriorating the TiN diffusion barrier characteristics.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.682-689
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• 1995

In order to refine the grain size of Mg-Zn alloy 0.5 to 6wt.%Cu or Si elements were added. Alloy ingot was made under vacuum atmosphere of 4 ${\times}$ 10$\^$-4/ Torr in the quartz tube coated by BN. Grain size and hardness were measured after solution treatment for 8 hours at 435$^{\circ}C$. Optimal condition for grain size refining effect was obtained at the minimum composition of 2wt.%Cu or 1.5wt.%Si addition to Mg-6wt%Zn alloy. Age hardening behavior was experimented at the optimal compositions of the Mg-6wt.%Zn, Mg-6wt.% Zn-2wt.%Cu and Mg-6wt.% Zn-1.5wt.%Si. The hardness increment due to fine grain size was higher at the Mg-Zn-Cu alloy system, but that due to age hardening was higher at the Mg-Zn-Si alloy system.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.151.1-151.1
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• 2017

This work studied the corrosion behavior of AZ31 Mg alloy galvanically coupled with Cu during immersion in 0.1 and 0.5 M NaCl solutions by in-situ observation and galvanic corrosion current measurement using a zero resistance ammeter. The corrosion behavior of AZ31 Mg alloy was also studied by salt spray test. The average galvanic corrosion density during 2 h immersion in 0.1 NaCl solution was found to decrease as an exponential function with increasing the surface area ratios between AZ31:Cu or with increasing the distance between AZ31 and Cu. The corrosion of electrodeposited Cu on AZ31 Mg alloy was concentrated at the area next to Cu (about 5 mm for immersion test and 2 mm for salt spray test) and pitting corrosion was accelerated at the area beyond the severely corroded area by the galvanic coupling effect.

• Korean Journal of Materials Research
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• v.31 no.11
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• pp.642-648
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• 2021

The precipitation effect of Al-6%Si-0.4%Mg-0.9%Cu-(Ti) alloy (in wt.%) after various heat treatments was studied using a laser flash device (LFA) and differential scanning calorimetry (DSC). Solid solution treatment was performed at 535 ℃ for 6 h, followed by water cooling, and samples were artificially aged in air at 180 ℃ and 220 ℃ for 5 h. The titanium-free alloy Al-6%Si-0.4%Mg-0.9%Cu showed higher thermal diffusivity than did the Al-6%Si-0.4%Mg-0.9%Cu-0.2%Ti alloy over the entire temperature range. In the temperature ranges below 200 ℃ and above 300 ℃, the value of thermal diffusivity decreased with increasing temperature. As the sample temperature increased between 200 ℃ and 400 ℃, phase precipitation occurred. From the results of DSC analysis, the temperature dependence of the change in thermal diffusivity in the temperature range between 200 ℃ and 400 ℃ was strongly influenced by the precipitation of θ'-Al₂Cu, β'-Mg₂Si, and Si phases. The most important factor in the temperature dependence of thermal diffusivity was Si precipitation.

• Journal of Korea Foundry Society
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• v.22 no.2
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• pp.82-88
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• 2002

Al-5.5Zn-2.5Mg-l.5Cu semi-solid slurry was prepared by cooling the liquid metal with a low superheat to a solid and liquid co-existing temperature. Relatively round solid particles could be obtained in the slurry through the simple process. The prepared slurry was deformed into the metallic mold by a press and the mechanical properties of obtained specimens were investigated. Mold filling ability of the alloy slurry was also investigated and compared with that of A356 alloy. Al-Zn-Mg-Cu alloy showed lower mold filling ability than A356 alloy probably because small amount of eutectic phase is present and the heat of fusion generated during solidification is smaller than that of A356 alloy.

• Journal of Korea Foundry Society
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• v.5 no.3
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• pp.19-26
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• 1985

This study has been carried out to examine into wettability of Cu-5%Sn alloy in $Al_2O_3$, MgO, $SiO_2$ and graphite, respectively and investigated into the change in macrostructure of Cu-5%Sn alloy according to kind and mixing rate of mold-coating. The results obtained from the experiment are summerized as follows; 1. Cu Cu-5%Sn alloy, wettabilities of $Al_2O_3$ and MgO were good, on the other hand, wettabilities of $SiO_2$ and graphite were bad. 2. The fine equiaxed zone was created because of the role of $Al_2O_3$ and MgO as preferential nucleation sites. 3. Notwithstanding change of mixing rate of $SiO_2$ in mold coating the equixed zone was not created. 4. The area of equiaxed zone was varied according to mixing rate in the case of using $Al_2O_3$ and MgO in mold-coating.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.695-702
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• 1999

We have explored the factors affecting the resistivity of Cu (Mg) alloy, which was prepared by sputtering. The results show that the resistivity is a function of Mg content, annealing temperature, annealing time, and Cu-alloy thickness. Addition of Mg to copper increases the resistivity through solute scattering. In addition, increasing Mg content promotes the interfacial reaction between Mg and SiO$_2$ to produce the free silicon and the generated free silicon dissolves into copper, resulting in a significant increase of resistivity. Furthermore, increasing oxidation temperature rapidly decreases the resistivity at the initial stage of oxidation and then continues to increase the resistivity to the saturation value with increasing oxidation time. The saturation value depends on the residual Mg content and the thickness of the alloy. TEM and AES analyses reveal that dense, uniform MgO grows to the limiting thickness of about $150\AA$. However, interfacial MgO does not show the limiting thickness, instead continues to grow until Mg is completely exhausted. From these facts, we proposed the maximum available Mg content needed to from the dense MgO on the surface and suppress the excessive interfacial reaction.

• Journal of Korea Foundry Society
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• v.35 no.4
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• pp.67-74
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• 2015

In this study, Mg-Zn alloys are investigated in terms of their thermal properties after an addition of Cu. Al element is added to improve the mechanical properties and castability in general case. However, it was excluded here because it significantly decreases the thermal conductivity. On the other hand, Zn was added as a major element, which had less influence on reducing the conductivity and can complement the mechanical properties as well. Cu was also added, and it improved the heat transfer characteristics as the amount was increased. The composition ranges of Zn and Cu are 6 wt.% and 0~1.5 wt.%, respectively. Mg-6Zn-xCu alloy was prepared by a gravity casting method using a steel mold and then the thermal conductivity and the microstructure of the as-cast material were investigated. By measuring the density_(${\rho}$), specific heat_(Cp) and thermal diffusivity_(${\alpha}$), the thermal conductivity_(${\lambda}$) was calculated by the equation ${\lambda}={\rho}{\cdot}Cp{\cdot}{\alpha}$. As the amount of Cu increased in the Mg-6Zn-xCu alloy, the heat transfer characteristics were improved, resulting in a synergistic effect which is slow when the added Cu exceeds 1 wt.%. In order to investigate the relative thermal conductivity/emission of the Mg-6Zn-xCu alloy, AZ91 and AZ31 were experimentally evaluated and compared using a separate test equipment. As a result, the Mg-6Zn-1.5Cu alloy when compared to AZ91 showed improvements in the thermal conductivity ranging from 30 to 60% with a nearly 20% improvement in the thermal emission.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.90-90
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• 1999

• 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.