• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.74-78
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• 2024

We have studied the effects of Ag on the characteristics of Sn₄₈In₅₂Ag_x (wt%) low-melting solders for photovoltaic ribbons. The Sn₄₈In₅₂ (wt%) solder coexisted in the InSn₄ and In₃Sn alloys. Ag atoms added in the solder formed an AgIn₂ alloy by reacting with some part of In atoms, while they did not react with Sn atoms. The addition of Ag atoms in the Sn₄₈In₅₂Ag_x (wt%) solders showed useful results; an increase in peel strength and a decrease in melting temperature. The peel strength of the ribbon plated with the Sn₄₈In₅₂ (wt%) solder was 53.6 N/mm², and that of the Sn₄₈In₅₂Ag₁ (wt%) solder largely increased to 125.1 N/mm². In the meanwhile, the melting temperature of the Sn₄₈In₅₂ (wt%) solder was 119.2℃, and that of the Sn₄₈In₅₂Ag₁ (wt%) solder decreased to 114.0℃.

• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.67-73
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• 2015

This is a basic research for improving soft magnetic property of Fe based nano crystalline alloy powder core. The main study is done around characteristics of permeability, core loss, and DC bias depending on amount of insulation coating agent and particle size. First, $Fe_{73.5}Si_{13.5}B_9Nb_3Cu_1$ amorphous alloy ribbon was fabricated by using the planar flow casting (PFC) device. Then, heat treatment and ball milling were done to obtain alloy powder. The amount of polyether imide (PEI) added to it was varied by 0.5, 1.0, 2.0, 2.5 wt% to have compression molding into $16ton/cm^2$. After going through crystalline heat treatment, the made toroidal nano crystalline powder core ($OD12.7mm^*ID7.62mm^*H4.75mm$) had smaller permeability as amount of insulation coating agent decreases. However, it was found out that core loss and DC bias characteristics have been improved. The reason for this results were expected to be because green density of power core decreases as amorphous alloy powder particles become smaller as amount of alloy powder insulation coating agent increases, it was determined that 1 wt% of insulation coating agent is appropriate. Also, for powder core made based on alloy powder size with amount of insulation coating agent fixed at 1 wt%, effective permeability and core loss were outstanding as particle size became bigger. However, characteristics of DC bias became worse as applied DC field increases. This is expected to be due to insulation effect, residual pores, or molding density of powder core resulting from thickness of coating on surface of alloy powder.

• Korean Journal of Materials Research
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• v.12 no.2
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• pp.140-145
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• 2002

This study was conducted to investigate the brazing characteristics between Zircaloy-4 nuclear fuel cladding tubes and bearing pads with filler metals of amorphous $Zr_{1-x}Be_x$(0.3$\leq$x$\leq$0.5) binary alloy, in which they were produced in the ribbon form by the melt-spinning metod. The crystallization behavior, stability, hardness and micro-structure of brazed zone were examined by X-ray diffraction, differential scanning calorimetry, micro-Vickers hardness test, optical microscopy, and transmission electron microscopy. $Zr_{1-x}Be_x$(0.3$\leq$x$\leq$0.4) amorphous alloys were crystallized to $\alpha$-Zr with increasing the temperature, and the rest were transformed to ZrBe$_2$at higher temperatures. On the other hand, $Zr_{1-x}Be_x$(0.4$\leq$x$\leq$0.5) amorphous alloys were crystallized to $\alpha$-Zr and ZrBe$_2$, simultaneously. The thickness of the layer brazed with amorphous alloy was increased with increasing the beryllium content due to the higher diffusion of Be. The morphology of brazed layer with PVD Be filler metal showed dendrite while that brazed with amorphous alloys appeared globular. Micro-Vickers hardness of brazed zone increased as the beryllium content of filler metal was decreased.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.98-104
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• 2014

Photovoltaic (PV) cell is considered as one of the finest ways to utilize the solar power. A study of improving solar cell's efficiency is important because the lifetime of solar cell is determined by photovoltaic module technology. Therefore, oxidation (and/or corrosion) of solder materials will be one of the primary yield and long-term reliability risk factor. Recently, the development of lead-free solder alloy has been done actively about lead-free solder alloys of the thermodynamic and mechanical properties. However, the oxidation behavior have rarely been investigated In this study, the oxidations of 60 wt% Sn-40 wt% Pb, 62 wt% Sn-36 wt% Pb -2 wt% Ag, 50wt% Sn-48 wt% Bi-2 wt% Ag alloys for the interconnect ribbon after exposure in atmosphere at $100^{\circ}C$ for several times were investigated. The wettability of 62 wt% Sn-36 wt% Pb-2 wt% Ag and 50 wt% Sn-48 wt% Bi-2 wt% Ag solders was also studied to compare with that of 60 wt% Sn-40 wt% Pb alloy. The results howed that the zero cross time and the wetting time of 50 wt% Sn-48 wt% Bi-2 wt% Ag solder were better than other two samples. The surface of tested samples was analyzed by XPS. The XPS result showed that in all samples, SnO grew first and then the mixture of SnO and $SnO_2$ was detected. $SnO_2$ grew predominantly for the long time aging. Moreover XPS depth profile analysis has found surface enrichment of tin oxide.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.3
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• pp.236-243
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• 1995

Since amorphous alloys have been known to have better mechanical and chemical properties than crystalline alloys of the same composition, a great number of studies on the formation of Al-based amorphous alloys have been carried out actively. However, little has been obtained about the effect of Rare-Earth metal and Transition metal addition on amorphous phase formed by melt spinning method. This study included fabrication of amorphous alloy $Al_{85}Ce_5Ni_{10}$ by melt spinning methods and DTA, XRD, TEM analysis to determine crystalization behavoir. Annealing treatments were carried out in Ar atmosphere under isothermal and nonisothermal conditions. The diffraction pattern of non-heated ribbons showed broad form characteristic of glass metallic alloy. The crystallization of amorphous $Al_{85}Ce_5Ni_{10}$ takes place eutedtoidly by homogeneous formation of Al and MS-1, followed by precipitation of the $Al_{11}Ce_3$ and later $MS-1{\rightarrow}Al_3Ni$ transformation.

• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.446-452
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• 1988

To obtain detailed information on the metastable and the equilibrium phases in rapidly solidified Al-(Fe,Ce) alloys, analysis of X-ray diffraction pattern has been carried out. It has been found that the metastable phase formed in Al-Fe alloys including up to 6wt%Fe is $Al_6Fe$ and the equilibrium phase is $Al_3Fe$. Any X-ray diffraction peak corresponding to the equilibrium phase $Al_{13}Fe_4$ has not been observed during aging. In Al-4wt%Fe alloy, which is ribbon shape with thickness less than $70\;{\mu}m$, aged at $400^{\circ}C$ for 1h after rapid solidification, unidentified phase has been found. In Al-4wt%Ce alloy, only X-ray diffraction peak corresponding to the equilibrium phase, $Al_4Ce$ has been observed. It has been found that the metastable phase Formed in Al-Fe-Ce alloys including up to 6wt% Fe and 4wt% Ce is $Al_6Fe$ and the equilibrium phases are $Al_3Fe$ and $Al_{10}CeFe_2$.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.38-46
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• 1991

Effects of aging treatment on the microstructures and microhardness of a rapidly solidified Al-Li-Cu-Mg-Zr alloy were investigated by differential scanning calorimetry(DSC) and transmission electron microscopy(TEM). The as-melt-spun ribbon was consisted of fine ${\delta}^{\prime}$ and icosahedral intermetallic compound which were precipitated in the matrix. Two exothermic peaks with the range of $120^{\circ}C-190^{\circ}C$ and $280^{\circ}C-344^{\circ}C$ corresponded to ${\delta}^{\prime}$ and ${\theta}^{\prime}$, S', $T_1$ precipitating reaction respectively, and two endothermic peaks with the range of $190^{\circ}C-280^{\circ}C$ and $344^{\circ}C-550^{\circ}C$ corresponded to dissolution of ${\delta}^{\prime}$ and ${\theta}^{\prime}$, S', $T_1$ respectively in DSC curves. Peak hardness value was obtained at $210^{\circ}C$ for 1 hr aging treatment.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.478-482
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• 1995

The iron-based Metglas 2605S3A amorphous alloy ribbons are annealed at $435^{\circ}C$ for various periods from 5 to 210 min, and the effect of annealing is investigated on the dc magnetic properties of the ribbon. Typical square-type hysteresis loops are observed for the ribbons annealed fo 5 min, indicative of the nearly complete removal of residual stresses which are produced during melt-quenching. As the annealing time increases, the coercivity increases and the shape of hysteresis loops transforms to round type and finally to sheared one at the longest annealing time of 210 min. These results may be explained by the formation of clusters with chemical shortorder and very fine crystallites (at the annealing time of 210 min), and the diffusion-induced stresses during the formation of the clusters. For the samples annealed for 5 min, very good dc properties of the squareness ratio, coercivity and maximum permeability are observed, but, rather unexpectedly, the initial permeability is found to be very low. These results are considered to be due to a simple domain structure consisting of very small number of $^{\circ}$ domains.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.211-217
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• 1996

The effects of Al addition to Fe-B-Nb-Cu alloy for improving the high-frequency magnetic properties and the magnetic properties of ultrathin $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ nanocrystalline alloy ribbons with the thickness less than $10\;\mu\textrm{m}$ were investigated. It was found that the effective permeability at frequencies over- 100 kHz was very high and the core loss was very low for the composition $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ alloy. Moreover, the reduction of the ribbon thickness below $10\;\mu\textrm{m}$ was very effective in improving their permeability and the core loss characteristics up to the MHz frequency range. The values of effective permeability at 1 MHz and core loss at 0.2 T, 1 MHz were 5,000 and 1.4 kW/kg, respectively. It was considered that these results were due to far refined $\alpha-Fe$ phase structure with grain size less than 10 nm and domain structure modification.