• Proceedings of the KWS Conference
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• 2003.11a
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• pp.83-85
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• 2003

This paper is investigated the shear strength by using the micro shear-punch test method for Sn-37Pb alloy, binary and ternary alloys of environment-friendly Pb-free solder alloys which would be surely applicable to the electronic packages. As a result, in case of Max. shear strength, Sn-4Ag-0.5Cu has the highest value and Sn-37Pb has the lowest value on every condition of experiment temperature. Also, In case of Pb-free solder joint specimens, it was found that Pb-free solder alloys have higher value of shear strength than eutectic Sn-Pb solder alloy and Sn-4Ag-0.5Cu has the highest value.

• Journal of Technologic Dentistry
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• v.7 no.1
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• pp.13-18
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• 1985

Casting alloys, both precious and non-precious, were by heat in order to observe the change in HB and the results were : 1. The hard treatment showed 1.4 - 1.5 times as high as the soft treatment in HB. 2. The experiment shows that Au-Pt should be contained more than 75% to prevent color change. 3. Cu by hard teatment played the greatect part in creasing the solidity of Ag-Cu alloy. 4. Casting Co-Cr alloys showed little difference of HB in heat treatment.

• Journal of the Korean institute of surface engineering
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• v.37 no.4
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• pp.234-241
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• 2004

Cavitation erosion properties of the Cu-9Al-4.5Ni-4.5Fe alloys (Al-bronze) surface-modified by flame quenching process have been investigated. After flame quenching at above $T_{\beta}$, the surfaces of Al-bronze with $\alpha$ + $\textsc{k}$ structure have been changed into the $\alpha$ + $\beta$' martensite phases by the eutectoid reaction of $\alpha$ + $\textsc{k}$\longrightarrow$\beta$ followed by the martensite transformation of $\beta$\longrightarrow$\beta$'. As a result of cavitation test, the measured incubation time and erosion rate of the $\alpha$ + $\beta$' alloy was 1.2 times higher and 1.5 times lower, respectively, compared to those of the conventional $\alpha$ + $\textsc{k}$ alloys, showing a remarkable increase of cavitation resistance with the formation of $\beta$' martensite. This is attributed to a preferential erosion of the $\textsc{k}$ precipitates that show the lowest resistance among the $\alpha$, $\textsc{k}$, $\beta$' phases under cavitation loading.ases under cavitation loading.

• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.156-163
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• 1995

Solidification of aluminum alloys under moderate pressures has been investigated. Interfacial heat transfer coefficient at the casting/mold interface varies with time after pouring the molten metal into the die cavity, and therefore plays an important role in determining solidification sequence. The heat transfer coefficients were evaluated by using an inverse problem method, based on the measured temperature distribution. The calculated heat transfer coefficients were used for solidification simulation in the squeeze casting process. The effects of applied pressure and positions of insulation in the mold have also been investigated on solidification microstructures and on the formation of macrosegregation of Al-4.5wt.%Cu alloys.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.281-284
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• 2003

The microstructural changes of Al-Zn-Mg-Cu alloy containing Sc during hot extrusion and post heat treatment is investigated. Two kinds of Al-Sc alloys with different alloying elements (B1, B2) are hot extruded to make I-shape bars at 380$^{\circ}C$, then the bars are solution treated at 480$^{\circ}C$ for 2hrs followed by artificial aging at 120$^{\circ}C$ for 24hrs. The interior microstructure of as extruded bar consists of elongated grains, however, fine equiaxed grains are mainly observed around surface. The microstructural gradient suggests that different restoration process can proceed during the hot extrusion. For B1 and B2, different grain growth behaviors are found around the surface during the post heat treatment. Rapid grain growth behavior around the surface is discussed related with the crystallographic orientation of the grain.

• Journal of Powder Materials
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• v.2 no.3
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• pp.208-215
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• 1995

The aging effects on the characteristics of the melt spun Cu based shape memory alloys have been investigated by the microhardness test, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. After aged for specific times, hardness of the ribbons began to increase and shape memory capacity diminished. At the initial stage of aging the austenitic transformation temperatures increased gradually, but at last became nearly constant: That is, the aging deteriorated the thermal stability. The increase in hardness was due to the formation of the $\gamma_2$ precipitates. The loss in the shape memory capacity was due to the decrement of solute atoms in the matrix by the formation of the $\gamma_2$ precipitates. In this study, it was confirmed that Mn is an effective element for Improving the thermal stability.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.557-558
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• 2006

In all conventional sintered PM products, the pores present are of two types, primary and secondary. Primary pores forming during compaction and latter during sintering, due to penetration of formed liquid through the matrix grain boundary. Effect of carbon addition on diffusion of Cu in SH737-2Cu system was investigated. After compaction and transient liquid phase sintering at $1120^{\circ}C$ and $1180^{\circ}C$, samples were characterized for densification, showing rise in sintering density and reduction in swelling on carbon addition. Quantitative microstructural characterization (shape factor and pore size) revealed bimodal distribution for 0% carbon, more rounded pores for 0.9% carbon and higher sintering temperature, and pore coarsening at higher sintering temperature.

• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.379-384
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• 1997

Al-15Cu-lMg alloys have been directionally solidified in 3mm diameter alumina tubes under the conditions of $760^{\circ}C$ of furnace temperature and 12 cm/hr of furnace moving velocity(V). By analyzing the evolution of the temperature profiles along the alloy length, the position of the solid/liquid interface, temperature gradient(G) and local growth velocity (R) were determined. These growth characteristics were compared for 6, 10, 14 cm length alloys. Steady state growth region was obtained in 15 cm length alloy, not in 6, 10 cm.

• Journal of Powder Materials
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• v.27 no.6
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• pp.449-457
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• 2020

Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.427-431
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• 1995

The influence of Nd and B contents on the magnetic properties and structures of ${\alpha}-Fe$ based Nd-(Fe,Co)-B-Mo-Cu alloys was investigated. $Nd_{4}{(Fe_{0.9}Co_{0.1})}_{92-x}B_{x}Mo_{3}Cu_{1}$ and $Nd_{x}{(Fe_{0.9}Co_{0.1})}_{86-x}B_{10}Mo_{3}Cu_{1}$ amorphous alloys prepared by rapid solidification process were crystallized to form nanocrystalline structure. The increase of B content in $Nd_{4}{(Fe_{0.9}Co_{0.1})}_{92-x}B_{x}Mo_{3}Cu_{1}$ nanocrystalline resulted in the change of stucture of soft phase in the sequence of ${\alpha}-Fe$->${\alpha}-Fe+Fe_{3}B$->$Fe_{3}B$. The coercivitis of the alloys were increased with increasing B content and was 263 kA/m at x=18. On the contrary, the remanence has shown an opposite trends. The increase of Nd content in $Nd_{x}{(Fe_{0.9}Co_{0.1})}_{86-x}B_{10}Mo_{3}Cu_{1}$ nanocrystalline containing ${\alpha}-Fe$ as main phase had no effect on the structure and improved coercivity up to 256 kA/m. However, the remanence was decreased from 1.4 T to 1.15 T according to the increase of Nd content.