• Journal of Korea Foundry Society
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• v.22 no.6
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• pp.288-292
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• 2002

Ni-base amorphous alloys were manufactured using melt-spinning and Cu-mold die casting methods. Amorphous formability, the supercooled liquid region before crystallization and mechanical properties were examined. The reduced glass transition temperature and the supercooled liquid region of $Ni_{51} Nb_{20} Zr_9 Ti_9 Co_8 Cu_3$alloy were 0.621 and 46 K respectively. $Ni_{51} Nb_{20} Zr_9 Ti_9 Co_8 Cu_3$ alloy was produced in the rod shape 3mm diameter using the Cu-mold die casting. Hardness, compression strength, elongation and elastic modulus of the alloy were 850 DPN, 2.75 GPa, 1.8% and 150 GPa respectively. Moreover, compression strength of 2.75 GPa was the highest value in the amorphous bulk alloy produced up to now.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.507-510
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• 1995

A heat-treatment method of pre-annealing and then flash annealing(FA) has been used to improve the soft magnetic properties of nanocrystalline $Fe_{76}CuSi_{13}B_{10}$ and $Fe_{74}CuNb_{3}Si_{12}B_{10}$ alloys. Outstanding magnetic properties of nanocrystalline $Fe_{74}CuNb_{3}Si_{12}B_{10}$ alloy were attained by flash-annealing in air after annealed at $500^{\circ}C$ for 0.5hr below the crystallization temperature. The same results were obtained for $Fe_{74}CuSi_{13}B_{10}$ alloy. The measurment of relief of stress and X-ray diffraction were used to analyze the effect of flashannealing.

• Journal of Korea Foundry Society
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• v.18 no.5
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• pp.439-449
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• 1998

Formation of oxide inclusions in the molten aluminium alloys during solidification is investigated. The oxidation tendency of both Al-4.5wt%Cu and Al-7wt%Si alloys is increased with melt temperature, particularly over $700^{\circ}C$. However, an Al-5wt%Mg alloy exhibits a decreasing mode over $800^{\circ}C$. The oxidation behavior with holding time shows the S curve shape for all of the alloys. It is shown that the mechanism of oxidation of Al-5wt%Mg alloy has a two step process different from that of Al-4.5wt%Cu and Al-7wt%Si alloys. The species and morphology of oxide inclusions in each alloy is also shown. The microstructure was more coarsened during solidification when the melt contains a large amount of oxide inclusion than when it doesn't. This result can be explained in terms of both the hindrance of heat extraction by oxide film formed on the aluminium melt and the difference of heat capacity between the aluminium melt and oxide inclusion during solidification.

• Journal of Korea Foundry Society
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• v.19 no.6
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• pp.456-465
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• 1999

The overall objective of this study is to investigate the effect of Ag addition on the mechanical properties and microstructure of rapid solidified 7000 Al series alloys. Al-Zn-Mg-Cu alloys with small amounts of Ag was fabricated into the powder by gas atomization. The powder was extruded after the cold compaction and degassing and then followed by T6 heat treatment. Microstructure observation, phase analysis, room and high temperature tensile test and hardness test were pursued. The tensile strength and hardness of Ag-added alloy after heat treatment was increased with increasing Ag contents. However, the elongation of extruded alloys was not increased as much as to be expected. The reason of this result seems to be related to $the{\Omega}$ phase, which contribute to the high temperature strength stability of Al-Cu-Zn alloys through the formation of eutectoid with Ag addition.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.29-33
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• 2014

The electrochemical characteristics of Al-Si casting alloys (Al-10%Si, Al-9%Si, Al-7%Si) in 3.5% NaCl solution at room temperature was studied using potentiodynamic techniques. The electrochemical values of corrosion potential($E_c$), corrosion current density($I_c$) and corrosion rate(mpy) were examined. The Al-Si alloys had several compounds such as $Mg_2Si$, ${\pi}$-$Al_8Si_6Mg_2Fe$ and $Al_2CuMg$ which could affect corrosion resistance significantly. The potentiodynamic polarization curve exhibited typical active behavior in anodic polarization curve. The major corrosion mechansim for the Al-Si alloys were pitting and grain boundary corrosion. As increasing Si and Cu contents, their corrosion resistance was decreased.

• Journal of Powder Materials
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• v.30 no.3
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• pp.255-261
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• 2023

Aluminum alloys are widely utilized in diverse industries, such as automobiles, aerospace, and architecture, owing to their high specific strength and resistance to oxidation. However, to meet the increasing demands of the industry, it is necessary to design new aluminum alloys with excellent properties. Thus, a new method is required to efficiently test additively manufactured aluminum alloys with various compositions within a short period during the alloy design process. In this study, a combinatory approach using a direct energy deposition system for metal 3D printing process with a dual feeder was employed. Two types of aluminum alloy powders, namely Al6061 and Al-12Cu, were utilized for the combinatory test conducted through 3D printing. Twelve types of Al-Si-Cu-Mg alloys were manufactured during this combinatory test, and the relationship between their microstructures and properties was investigated.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.88-89
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• 1998

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.146-146
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• 1994

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.38-38
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• 1997

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.233.2-233.2
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• 2003