• Transactions on Electrical and Electronic Materials
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• 제12권1호
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• pp.20-23
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• 2011

Amorphous Ti-(50-x)Ni-xCu (at%) (x = 20, 25, 27, 30) alloy ribbons were prepared by melt spinning. Subsequently, the crystallization behavior of the alloy ribbons was investigated by X-ray diffraction and differential scanning calorimetry. ${\Delta}T$ (the temperature gap between $T_g$ and $T_x$) increased from 33 K to 47 K and the wavenumber ($Q_p$) decreased from 29.44 $nm^{-1}$ to 29.29 $nm^{-1}$ with increasing Cu content from 20 at% to 30 at%. The activation energy for crystallization decreased from 188.5 kJ/mol to 170.6 kJ/mol with increasing Cu content from 20 at% to 25 at%; afterwards, the activation energy remained near constant. Crystallization occurred in two-stage: amorphous-B2-$TiCu_2$ in Ti-Ni-Cu alloys with Cu content less than 25 at%, while it occurred in three-stage; amorphous-B2-TiCu-$TiCu_2$ in Ti-Ni-Cu alloys with Cu content more than 27 at%.

• E2M - 전기 전자와 첨단 소재
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• 제10권9호
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• pp.938-944
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• 1997

Cu-Ni thin film strain gauges for diaphragm-type pressure sensors were developed. Thin films of Cu-Ni alloys of various compositions were deposited onto glass and stainless steel substrates by RF magnetron sputtering. The effects of composition substrate temperature Ar partial pressure and aging on the electrical properties of Cu-Ni film strain gauges in the thickness range 500~2000$\AA$ are discussed. The maximum resistivity(95.6 $\mu$$\Omega$cm) is obtained from 53wt%Cu-47wt%Ni films while the temperature coefficient of resistance(TCR) becomes minimum(25.6ppm/$^{\circ}C$). The gauge factor is about 1.9.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.94-98
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• 2003

The microstructure of Sn1.8Bi0.8Cu0.6In alloys was evaluated at various aging time. The bumps of Sn1.8Bi0.8Cu0.6In alloys after reflowed at $250^{\circ}C$ were well-formed and had 260um height. The craters on the bumps, however, were observed. Intermetallic compounds formed on the interface between so]der and Cu/Ni UBM were consist of $(Cu,Ni)_6Sn_5$. As aging goes on up to 1000hours, the composition of Ni changed from $6.63\%$ at initial stage(as-reflowed) to $13.47\%$ at final stage(1000hours aging ). In addition, after 500hours aging, the floating of IMC to the solder was observed.

• 한국안전학회지
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• 제24권1호
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• pp.26-30
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• 2009

Shape memory recoverable stress and strain of Ti-42.5at%Ni-10at%Cu alloys were measured by means of constant temperature tensile tests. The alloys' transformation behavior is B2 - B19 by DSC result. The strain by tensile stress were perfectly recovered by heating at any testing conditions but shape memory recoverable stress increased to 66MPa and then slightly decreased. Transformation temperatures from thermal cycling under constant uniaxial applied tensile loads linearly increased by increasing tensile load and their thermal hysteresis are about 110K and their maximum recoverable strain is 6.5% at 100MPa condition.

• 한국분말재료학회지
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• 제17권6호
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• pp.477-481
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• 2010

Cu-Sn based alloys were manufactured by gas atomization spray casting route in order to achieve a fine scale microstructure and a high tensile strength. The spray cast Cu-10Sn-2Ni-0.2Si alloy had an equiaxed grain microstructure, with no formation of brittle ${\delta}-Cu_{41}Sn_{11}$ phase. Aging treatment promoted the precipitation of finely distributed particles corresponding to ${\delta}-Ni_2Si$ intermetallic phase throughout the $\alpha$-(CuSn) matrix. The cold-rolled Cu-Sn-Ni-Si alloy had a very high tensile strength of 1200 MPa and an elongation of 5%. Subsequent aging treatment at $450^{\circ}C$ for 1h slightly reduced the tensile strength to 700 MPa and remarkably increased the elongation up to 30%. This result has been explained by coarsening the precipitates due to over aging and reducing the dislocation density due to annealing effects.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 추계학술발표 개요집
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• pp.163-165
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• 1994

• 열처리공학회지
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• 제10권1호
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• pp.20-29
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• 1997

Pure copper is widely used for base material for electrical and electronic parts because of its good electrical conductivity. However, it has such a low strength that various alloying elements are added to copper to increase its strength. Nevertheless, alloying elements which exist as solid solution elements in copper matrix severely reduce the electrical conductivity. The reduction of electrical conductivity can be minimized and the strengthening can be maximized by TMT(Thermo-Mechanical Treatment) in copper alloys. In this research, the effects of TMT on mechanical and electrical properties of Cu-Ni-Al-Si-P, Cu-Ni-Al-Si-P-Zr and Cu-Ni-Si-P-Ti alloys aged at various temperatures were investigated. The Cu alloy with Ti showed the hardness of Hv 225, electrical conductivity of 59.8%IACS, tensile strength of 572MPa and elongation of 6.4%.

• 열처리공학회지
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• 제25권6호
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• pp.292-298
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• 2012

In this study, Cu-2.5at.%Ni-1at.%Si alloys were fabricated by horizontal continuous casting system to improve the electrical conductivity and mechanical properties of Cu-Ni-Si alloy. Withdrawing speed was changed with 50, 100, 150 and 200 mm/min for the optimum manufacturing condition. Microstructure was observed using OM, FE-SEM and TEM. Electrical conductivity was measured by 4-point probe method and mechanical properties were tested. A horizontal continuous cast thin slab had sound macro and micro structures with partly crystallized structures. Electrical resistivity decreased with increasing annealing temperature from 250 to $850^{\circ}C$, with increasing annealing temperature The maximum hardness and tensile strength were Hv 130, 610 MPa at $550^{\circ}C$, respectively. With changing withdrawing speed from 50 to 150 mm/min, hardness, tensile strength, yield strength and elongation were Hv 60-65, 210-230 MPa, 65-75 MPa and 40-50%, respectively.

• 한국분말재료학회지
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• 제21권1호
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• pp.34-38
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• 2014

Cu-Ni alloys with unidirectionally aligned pores were prepared by freeze-drying process of CuO-NiO/camphene slurry. Camphene slurries with dispersion stability by the addition of oligomeric polyester were frozen at $-25^{\circ}C$, and pores in the frozen specimens were generated by sublimation of the camphene during drying in air. The green bodies were hydrogen-reduced at $300^{\circ}C$ and sintered at $850^{\circ}C$ for 1 h. X-ray diffraction analysis revealed that CuO-NiO composite powders were completely converted to Cu-Ni alloy without any reaction phases by hydrogen reduction. The sintered samples showed large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The pore size and porosity decreased with increase in CuO-NiO content from 5 to 10 vol%. The change of pore characteristics was explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

• 한국주조공학회지
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• 제28권1호
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• pp.31-36
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• 2008

Ti-Ni-Cu alloys are very attractive shape memory alloys for applications as actuators because of a large transformation elongation and a small transformation hysteresis. Rapidly solidified Ti-Ni alloy ribbons have been known to have the shape memory effect and superelasticity superior to the alloy ingots fabricated by conventional casting. In this study, solidification structures and shape memory characteristics of $Ti-Ni_{30}-Cu_{20}$ alloy ribbons prepared by melt spinning were investigated by means of DSC and XRD. Operating parameters to fabricate the amorphous ribbons were the wheel velocity of 55 m/s and the melt spinning temperature of $1500^{\circ}C$. The crystallization temperature was measured to be $440^{\circ}C$. The crystallized ribbons exhibited very fine microstructure after annealing at $440^{\circ}C$ for 10 minutes and $460^{\circ}C$ for 5 minutes and was deformed up to about 6.8% and 6.23% in ductile manner, respectively. Stress-strain curve of the ribbon exhibited a flat stress-plateau at 64 MPa and this is associated with the stress-induced a B2-B19 martensitic transformation. During cycle deformation with the applied stress of 220 MPa, transformation hysteresis and elongation associated with the B2-B19 transformation were observed to be $4.3^{\circ}C$ and 3.6%.