• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1000-1001
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• 2006

Two atomized alloy powders were pre-compacted by cold and subsequently hot forged at temperatures ranging from 653K to 845K. The addition of Cu and Mg causes a decrease in the eutectic reaction temperature of Al-10Si-5Fe-1Zr alloy from 841K to 786K and results in a decrease of flow stress at the given forging temperature. TEM observation revealed that in addition to Al-Fe based intermetallics, $Al_2Cu$ and $Al_2CuMg$ intermetallics appeared. The volume fraction of intermetallic dispersoids increased by the addition of Cu and Mg. Compressive strength of the present alloys was closely related to the volume fraction of intermetallic dispersoids.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1887-1892
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• 2021

The effect of gadolinium and boron on the texture development and magnetic properties of the texture controlled 23Cr-10NiCu duplex stainless steels were studied to develop a high performance neutron and electromagnetic shielding material. The 23Cr-10NiCu base alloy is composed of 60% of austenite and 40% of ferrite, whereas, the 23Cr-10NiCu-0.5Gd-0.8B modified alloy is composed of 66% of austenite, 27% of ferrite and 7% of CrFeB intermetallic compounds. The gadolinium and boron addition to the 23Cr-10NiCu base alloy increased mechanical properties. Microstructure observation showed that the small addition of 0.5 wt% gadolinium and 0.8 wt% boron to the alloy retarded to form texture at the same hot rolling conditions, and improved the maximum magnetism, residual magnetism and coercive force about 3%, 122% and 120%, respectively.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.435-443
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• 2001

As power durable RF SAW filters, AL-(0∼2wt%)Cu alloy multi-layered thin electrodes were deposited on 42° LiTaO$_3$ piezoelectric substrates by magnetron sputtering process, and then ladder-type RF SAW filters, satisfying the electrical specification of CDMA transmission band, were fabricated through optimizing SAW resonator structures. The temperature of film electrodes in SAW filter was increased with RF power, and reached the maxima to cause a failure of SAW filters at the cut-off frequencies of the RF filter band. As RF power increases, the electrodes of Al-Cu alloy showed higher power durability than that of pure Al. The multi-layer laminated film of Al-1wt.% Cu/Cu/Al-1wt%Cu resulted in the best power durability up to 4W of RF power. Every film electrode, however, was destroyed within seconds whenever applying a critical RF power to SAW filters, regardless of the composition and structure of film electrodes. The breakdown of film electrodes under FR power seems to believe due to the fatigue of electrodes caused by repetitive cyclic stress of surface acoustic wave, which is amplified as RF power increases.

• 한국분말재료학회지
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• 제17권6호
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• pp.470-476
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• 2010

In this study, Cu-10Sn and Cu-10Sn-2Ni-0.2Si alloys have been manufactured by spray casting in order to achieve a fine scale microstructure and high tensile strength, and investigated in terms of microstructural evolution, aging characteristics and tensile properties. Spray cast alloys had a much lower microhardness than continuous cast billet because of an improved homogenization and an extended Sn solid solubility. Spray cast Cu-Sn-Ni-Si alloy was characterized by an equiaxed grain microstructure with a small-sized (Ni, Si)-rich precipitates. Cold rolling of Cu-Sn-Ni-Si alloy increased a tensile strength to 1220 MPa, but subsequent ageing treatment reduced a ultimate tensile strength to 780 MPa with an elongation of 18%.

• 대한금속재료학회지
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• 제50권4호
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• pp.293-299
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• 2012

Ultrafine-grained or nanostructured alloys usually lack the strain hardening capability needed to sustain uniform tensile deformation under high stresses. To circumvent this problem, we fabricated the Cu-based composite reinforced with the 3-dimensionally interconnected $Cu_5Zr$ phase using the combined technique of rapid quenching and subsequent hot-rolling. The alloy exhibited a tensile ductility of ~2.5% together with a strength of 1.57 GPa, which exceeds the values of most commercially available Cu-Be alloys. In this study, we elucidated the structural origin of the high strength and tensile ductility of the developed alloy by examining the thermal stability of the $Cu_5Zr$ reinforcing phase and the energy (work) absorption capability of the Cu matrix.

• Archives of Metallurgy and Materials
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• 제65권4호
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• pp.1303-1306
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• 2020

TiNi alloys have excellent shape memory properties and corrosion resistance as well as high biocompatibility. This study investigated the effects of copper addition on the phase transitions and electrochemical corrosion behaviors of Ti₅₀Ni_50-xCu_x alloys. TiNi, Ti₅₀Ni₄₇Cu₃, Ti₅₀Ni₄₄Cu₆, and Ti₅₀Ni₄₁Cu₉ alloys were prepared using vacuum arc remelting followed by 4 h homogenization at 950℃. Differential scanning calorimetry and X-ray diffraction analyses were conducted. The corrosion behaviors of the alloys were evaluated using potentiodynamic polarization test in Hank's balanced salt solution at a temperature of 36.5 ± 1℃. The TiNi alloy showed phase transitions from the cubic B2 phase to the monoclinic B19' phase when the alloy was thermally cycled. The addition of copper to the TiNi alloy played a major role in stabilizing the orthorhombic B19 phases during the phase transitions of Ti₅₀Ni_50-xCu_x alloys. The shifts in the corrosion potential toward the positive zone and the low corrosion current density were affected by the amount of Cu added. The corrosion resistance of the TiNi alloy increased with increasing copper content.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.90-90
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• 1999

• 한국재료학회:학술대회논문집
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• 한국재료학회 2000년도 추계학술발표강연 및 논문개요집
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• pp.141-141
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• 2000

• 보존과학회지
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• 제35권4호
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• pp.309-316
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• 2019

This study intends to identify manufacturing techniques, including casting and alloy composition, of nine metal Buddha statues excavated from archaeological sites in Bagan, Myanmar. Two Buddha statues from Pyu city state(2^nd to 9^th century) contain Cu-Sn alloy(including <1 wt% Fe), with different relatively high percentages of Sn(16 wt% and 25 wt%) identified from each Buddha statue, and no Pb detected. Five Buddha statues from the Bagan dynasty contain various alloy ratios of Cu-Sn(including <1 wt% Pb), Cu-Sn-Pb, and Cu-Sn-Zn-Pb. All Buddha statues appear to be fabricated by casting, as there is no evidence of other heat treatments. The silver Buddha statue manufactured in the 18^th century includes >1% Cu besides silver with no additional metallic components identified. The bronze Buddha statue manufactured in the Konbaung dynasty(18^th century) is of Cu-Sn-Pb alloy. The Buddha statues of Pyu was alloy of Cu-Sn without Pb including ahigh percentage of The Buddha statues of both the Bagan and Konbaung dynasties are comprised of ternary Cu-Sn-Pb alloys, with a heterogeneous distribution of lead and tin. Some of Buddha statues of the Bagan dynasty have similar alloy ratios as those of Pyu, suggesting that similar manufacturing techniques were used.

• 열처리공학회지
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• 제11권2호
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• pp.111-120
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• 1998

The effects of chemical composition and thermal cycling on the martensitic transformation characteristics in Cu-rich, equiatomic and Zr-rich CuZr binary alloys have been studied by calorimetry. Only martensite could be indentified in equiatomic $Cu_{49.9}Zr_{50.1}$ alloy, while $Cu_{10}Zr_7$ and $CuZr_2$ intermetallic compounds as well as martensite were formed by rapid cooling from the melts in Cu-rich $Cu_{52.2}Zr_{47.5}$ alloy and Zr-rich $Cu_{48.4}Zr_{51.6}$ alloy, respectively. The $M_s$ temperature of $Cu_{49.9}Zr_{50.1}$ was $156^{\circ}C$ but those of $Cu_{52.5}Zr_{47.5}$ and $Cu_{48.4}Zr_{51.6}$ alloys, being $109^{\circ}C$ and $138^{\circ}C$, were lower than that of equiatomic $Cu_{49.9}Zr_{50.1}$ alloy. In all the alloys, the $M_s$ temperature has fallen but the $A_s$ temperature has risen, resulting in widening of the transformation hysteresis with thermal cycling. The anomalous characteristics in the transformation temperature are due to the presence of the intermetallic compounds i.e. $Cu_{10}Zr_7$ and $CuZr_2$ formed by an eutectoid reaction during thermal cycling in the temperature range between $-100^{\circ}C$ < $T_c$ < $400^{\circ}C$.