• Transactions of the Korean hydrogen and new energy society
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• v.4 no.1
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• pp.31-39
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• 1993

In order to improve the hydrogen storage capacity and the activation property of the $MmNi_{4.5}Al_{0.5}$ alloy, the multiphase alloy system are prepared by adding the excess Zr in $MmNi_{4.5}Al_{0.5}$ alloy. It is estimated from the X-ray diffraction pattern and the energy dispersive X-ray analysis that the 2nd phases in $MmNi_{4.5}Al_{0.5}Zr_x$ alloys are $ZrNi_3$, ${\beta}$-Zr. Their morphology is also examined by the scanning electron microscope, and it shows the needle-like precipitation. As the Zr contents increase, the activation time and the plateau pressure decrease, sloping of the plateau pressure increase. Amount of the 2nd phases increase with Zr contents in $MmNi_44.5Al_{0.5}Zr_x$ alloys. The $MmNi_44.5Al_{0.5}Zr_{0.05}$ alloy, which shows the maximum storage capacity and the strong resistance to intrinsic degradation, is considered as a proper alloy for hydrogen storage.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.506-513
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• 2010

The composite coatings of $(ZrO_2-8Y_2O_3)$/(Ni-22Cr-10Al-1Y) were prepared by the air plasma spraying method. They consisted of (Ni,Cr)-rich regions,$(ZrO_2-Y_2O_3)$-rich regions, and $Al_2O_3$-rich regions that were formed by oxidation of Al from (Ni-22Cr-10Al-1Y) during spraying. The coatings corroded at 800 and $900^{\circ}C$ in NaCl-$Na_2SO_4$ molten salts up to 50 hr. Ni, Cr and Al oxidized to NiO, $Cr_2O_3$ and ${\alpha}-Al_2O_3$, respectively. These oxides and $(ZrO_2-Y_2O_3)$ were dissolved off into the molten salts during hot corrosion, which resulted in the ever-lasting corrosion of the composite coatings. Chromium diffused out from the (Ni,Cr)-rich regions and oxidized to $Cr_2O_3$, which was most frequently found as surface scales. Aluminum retained in the (Ni,Cr)-rich regions were similarly diffused out.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.208-209
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• 2008

Ni/Ti/Al multilayer system was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Compared with conventional process using Ni, Ni/Ti/Al contact shows perfect ohmic behavior, and possesses much lower contact resistance of about $2.5\times10^{-4}\Omega{\cdot}cm^2$ after $930^{\circ}C$ RTA, which is about 2 orders of magnitude smaller than that of Ni contact. Contact resistance gradually increased as the RTA temperature was lowered in the range of 840 ~ $930^{\circ}C$, and about $3.4\times10^{-4}\Omega{\cdot}cm^2$ was obtained at the lowest RTA temperature of $840^{\circ}C$. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.82-88
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• 2019

Here, we report on nanocrystalline Si-Al-M (M = Fe, Cu, Ni, Zr) alloys for use as an anode for lithium-ion batteries, which were fabricated via a melt-spinning method. Based on the XRD and TEM analyses, it was found that the Si-Al-M alloys consist of nanocrystalline Si grains surrounded by an amorphous matrix phase. Among the Si-Al-M alloys with different metal composition, Ni-incorporated Si-Al-M alloy electrode retained the high discharge capacity of 2492 mAh/g and exhibited improved cyclability. The superior $Li^+$ storage performance of Si-Al-M alloy with Ni component is mainly responsible for the incorporated Ni, which induces the formation of ductile and conductive inactive matrix with crystalline Al phase, in addition to the grain size reduction of active Si phase.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.35-39
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• 2012

We studied interfacial reaction and bonding characteristics of a flip chip bonding with the viewpoint of formation behavior of intermetallic compounds. For this purpose, Sn-0.7Cu and Sn-3Cu solders were reflowed on the Al/Cu and Al/Ni UBMs. When Sn-0.7Cu was reflowed on the Al/Cu UBM, no intermetallic compounds were formed at the solder/UBM interface. The $Cu_6Sn_5$ intermetallic compounds formed by reflowing Sn-3Cu solder on the Al/Cu UBM were spalled from the interface, resulting in delamination of the solder/UBM interface. On the other hand, the $(Cu,Ni)_6Sn_5$ intermetallic compounds were formed by reflowing of Sn-0.7Cu and Sn-3Cu on the Al/Ni UBM and the interfacial bonding between the Sn-Cu solders and the Al/Ni UBM was kept stable.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.393-399
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• 2016

Flower-like nickel oxide (NiO) catalysts were coated on NiCrAl alloy foam using a hydrothermal method. The structural, morphological, and chemical bonding properties of the NiO catalysts coated on the NiCrAl alloy foam were investigated by field-emission scanning electron microscopy, scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. To obtain flower-like morphology of NiO catalysts on the NiCrAl alloy foam, we prepared three different levels of pH of the hydrothermal solution: pH-7.0, pH-10.0, and pH-11.5. The NiO morphology of the pH-7.0 and pH-10.0 samples exhibited a large size plate owing to the slow reaction of the hydroxide ($OH^-$) and nickel ions ($Ni^+$) in lower pH than pH-11.5. Flower-like NiO catalysts (${\sim}4.7{\mu}m-6.6{\mu}m$) were formed owing to the fast reaction of $OH^-$ and $Ni^{2+}$ by increased $OH^-$ concentration at high pH. Thus, the flower-like morphology of NiO catalysts on NiCrAl alloy foam depends strongly on the pH of the hydrothermal solution.

• Korean Journal of Materials Research
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• v.25 no.8
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• pp.391-397
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• 2015

NiO catalysts/$Al_2O_3$/FeCrAl alloy foam for hydrogen production was prepared using atomic layer deposition (ALD) and subsequent dip-coating methods. FeCrAl alloy foam and $Al_2O_3$ inter-layer were used as catalyst supports. To improve the dispersion and stability of NiO catalysts, an $Al_2O_3$ inter-layer was introduced and their thickness was systematically controlled to 0, 20, 50 and 80 nm using an ALD technique. The structural, chemical bonding and morphological properties (including dispersion) of the NiO catalysts/$Al_2O_3$/FeCrAl alloy foam were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and scanning electron microscopy-energy dispersive spectroscopy. In particular, to evaluate the stability of the NiO catalysts grown on $Al_2O_3$/FeCrAl alloy foam, chronoamperometry tests were performed and then the ingredient amounts of electrolytes were analyzed via inductively coupled plasma spectrometer. We found that the introduction of $Al_2O_3$ inter-layer improved the dispersion and stability of the NiO catalysts on the supports. Thus, when an $Al_2O_3$ inter-layer with a 80 nm thickness was grown between the FeCrAl alloy foam and the NiO catalysts, it indicated improved dispersion and stability of the NiO catalysts compared to the other samples. The performance improvement can be explained by optimum thickness of $Al_2O_3$ inter-layer resulting from the role of a passivation layer.

• Transactions of Materials Processing
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• v.7 no.4
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• pp.333-339
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• 1998

Hot torsion tests were conducted to investigate the high temperature deformation behavior of $Al_{85}Ni_{10}Y_5$ alloy extrudates fabricated with amorphous ribbons. The powder metallurgy routes, hot pressing and hot extrusion were used to fabricate the extrudates. Thermal properties of amorphous ribbons with different thickness as a function of aging temperature were studied by thin film x-ray dif-fraction (XRD) and differential scanning calorimetry(DSC). The Al phase crystallite firstly formed in the amorphous ribbons and its crystallization temperature($T_x$)Was ~210${\circ}C$ During the processings of consolidation and extrusion, nano-grained structure(~100 nm) was formed in the Al85Ni10Y5 alloy extrudates. The as-extrudated Al85Ni10Y5 alloy and the $Al_{85}Ni_{10}Y_5$ alloy annealed at 250${\circ}C$ for 1 hour showed a flow curve of DRV(dynamic recovery) during hot deformation at 400-550${\circ}C$. On the other hand, the $Al_{85}Ni_{10}Y_5$ alloy annealed at 400${\circ}C$ for 1 hour showed a flow curve of DRX(dynamic recrys-tallization) during hot deformation at 450-500${\circ}C$. Also the flow stress and flow strain of the $Al_{85}Ni_{10}Y_5$ alloy extrudate annealed at 400${\circ}C$ were higher than those at 250${\circ}C$.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.666-670
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• 2001

To improve the corrosion resistance of separator wet-seal area which is the barrier of commercialization of molten carbonate fuel cell(MCFC), Ni/Y/Al coating layer was fabricated by Ni electroplating and Y, Al e-beam PVD on AISI 316L stainless steel. NiAlY alloy coating layer was formed by heat treatment in reduction atmosphere at $800^{\circ}C$ for 5hr. Immersion test in molten carbonate salt at $650^{\circ}C$ was performed on as- received AISI 316L stainless steel and NiAlY coated specimen. According to cross sectional SEM/EDS observations, corrosion resistance of separator wet-seal area was improved by formation of dense oxide layers of Al and Y.

• Journal of Korea Foundry Society
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• v.7 no.4
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• pp.352-357
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• 1987

Recently there were many studies on the development of cast iron for increasing strength, thermal resistance and mechanical properties, etc. The effects on mechanical properties and variation of solidification structure of hypo-eutectic cast iron was investigated when Ni(Al) was added with a fixed quantity of Al(Ni) content. The conclusions are as follows. 1) Tensile strength was the maximum(over 41 kg/ $mm^2$) when Al is added about 0.72%. 2) Torsional strength and angle were increased with increasing Al content and represents maximum value, when Al and Ni content are 1.5 and 2.0%. 3) With increasing Ni content, tensile strength decreased because of the effect of graphite coarsening. But torsional strengths were increased with the appropriate addition of (Ni%+Al%) content because of the effect of strengthened matrix.