• Tribology and Lubricants
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• v.34 no.2
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• pp.67-73
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• 2018

Ni-Al intermetallic coating technology is an available method for the strengthening of aluminum substrate. In this study, Ni-Al intermetallics were coated on an aluminum substrate through a reaction synthesis process at a temperature lower than melting point of aluminum. And the sliding wear properties of the coatings have been investigated to verify their usability and compared the wear properties with those of a cast Al-12.5%Si alloy and an anodizing layer on aluminum. Results show that the wear rate of the coating layer greatly increased at 1 m/s and 1.5 m/s when compared with that of the cast Al-12.5%Si alloy. Much pitting damages were observed on the worn surfaces at these sliding speeds, unlike at other sliding speeds. The wear of the intermetallic coating layer at these sliding speeds seems to be increased by pitting as a consequence of adhesion. In contrast, wear of the coating layer at other speeds hardly occurs, regardless of wear periods. Nevertheless, the wear properties of the intermetallic coating layer on the aluminum substrate through the reaction synthesis process are more stable than those of anodized aluminum and are superior to those of the cast Al-12.5%Si alloy in a steady-state wear period.

• Journal of Korea Foundry Society
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• v.13 no.3
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• pp.276-284
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• 1993

The interfacial phenomena between intermetallic compounds and Al matrix have been studied at $680^{\circ}C$ for various holding time under argon atmosphere. Model experiments were performed using Fe, Ni and Ti wire to observe the interfacial phenomena. The interfacial phenomena between intermetallic compounds and Al matrix were analysed by optical microscope, SEM and EDX. The results of EDX and XRD showed that the interfacial zones of intermetallic compounds/Al matrix were composed of several intermetallic layers. The reaction layer was varied with holding time and heating temperature. The investigation of interfacial zones in the specimen as a function of heat treatment time at $680^{\circ}C$ indicated that the best heat treatment condition for squeeze casting was $680^{\circ}C$ for 5min.

• Journal of Welding and Joining
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• v.20 no.1
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• pp.97-102
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• 2002

The growth kinetics of intermetallic compound layers formed between the eutectic Sn-3.5Ag solder and the Cu and Ni/Cu pad by solid stateisothermal aging were examined. The interfacial reaction between the eutectic Sn-3.5Ag solder and the Cu and Ni/Cu pad was investigated at 70, 120, 150, $170^{\circ}C$ for various times. The intermetallic compound layer was composed of two phase: $Cu_6Sn_5$(${\varepsilon}-phase$) adjacent to the solder and $Cu_6Sn_5$(${\varepsilon}-phase$) adjacent to the copper and on solder/Ni pad the intermetallic compound layer was $Ni_3Sn_4$. Because the values of time exponent(n) have approximately 0.5, the layer growth of the intermetallic compound was mainly controlled by volume diffusion over the temperature range studied. The apparent activation energy for layer growth of total Cu-Sn($Cu_6Sn_5 + Cu_6Sn$), $Cu_6Sn_5$, $Cu_3Sn$ and $Ni_3Sn_4$ intermetallic compound were 64.82kJ/mol, 48.53kJ/mol, 89.06kJ/mol and 71.08kJ/mol, respectively.

• Analytical Science and Technology
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• v.5 no.1
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• pp.97-101
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• 1992

Potentiodynamic corrosion tests were conducted to know the corrosion characteristics of the NiTi intermetallic compound composed of pure Ni and Ti in artificial saline. Tafel extrapolation and linear polarization technique show similar results. Corrosion current Icorr and corrosion rate was increased in the order of NiTi

• Composites Research
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• v.16 no.3
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• pp.68-74
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• 2003

In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiA1$_3$ and was followed by the diffusional growth of Ni$_2$A1$_3$ between Ni and NiA1$_3$. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these 1aminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni$_3$Al having higher strength at room and high temperatures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.60-63
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• 2002

Metal/intermetallic laminated composites have been manufactured by SHS reactions between Ni and Al elemental metal foils. Microstructure showed that the intermetallic volume fraction was 55%, 45%, 35% in the 1:1, 2:1, 4:1 thickness ratio(Ni:Al) specimen and the main phases of the intermetallic were transformed from $Ni_2Al_3$ to NiAl when the thickness ratio was increased. Tensile strength and elongation were increased when the volume fraction of Ni metallic phase was increased. Under assumptions of isostrain condition, the tensile strength of metal/intermetallic laminated composites didn't obey the ROM due to the thermal residual stress and this was confirmed by X-ray residual stress analysis. Fracture toughness results by the SENB test showed R-curves with upward curvature based on LSB condition. Bridging stress based on LSB condition was determined by the curve fitting analysis, In-situ observed microstructure during fracture test showed that the various bridging mechanism such as crack bridging, crack branching and ductile failure of metallic layer were occurred

• Journal of Korea Foundry Society
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• v.31 no.2
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• pp.83-86
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• 2011

Ni-Al based intermetallic compounds of self-propagating high-temperature synthesis (SHS) by the heat of molten aluminum and been coated on the aluminum casting alloy. The effects of the pouring temperature in casting and the thickness of casting substrate on SHS of the coating layer have been investigated. The experimental result showed that the reaction of the coating layer was activated with increasing the pouring temperature in casting and the thickness of casting substrate. However, the aluminum substrate was re-melted by the heat of formation for intermetallic compounds. Then, it was considered that some mechanical or thermal treatments for elemental powder mixtures were required to control the heat of formation for intermetallic compounds in advance.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.80-93
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• 1994

The microstructure and fractography of the friction welded joint of Al to Cu have been investigated in order to understand the formation of intermetallic compounds and their effects on the failure in tensile test of the joint. The variation of welding pressure did not affect significantly the tensile strength of joint. However, the tensile strength of joint decreaed as welding time increased. The thickness of reaction layers of welded joints was several micro-meters and mainly composed of intermetallic compounds of $CuAl_2$, $Cu_9Al_4$ and Al+$CuAl_2$. The thickness of $CuAl_2$, $Cu_9Al_4$ was increased with welding time. However, $CuAl_2$ was gradually changed to $Cu_9Al_4$ which caused the decrease of tensile strength . Even though the morphology of fractured surfaces depended upon the welding time, the failure occurred along $CuAl_2$ intermetallic compound itself or between $CuAl_2$ and $Cu_9Al_4$ in most cases.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.61-67
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• 2003

The interfacial reaction between ultra-small 58Bi-42Sn solder and Au/Ni/Ti under bump metallurgy (UBM) for ultra-fine flip chip application was investigated. The ultra-small 58Bi-42Sn solder bump, about $46{\mu}m$ in diameter, was fabricated by using the lift-off method and reflowed using the rapid thermal annealing (RTA) system. The intermetallic compounds were characterized using a secondary electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an x-ray diffractometer (XRD). The faceted and polygonal intermetallic compounds were found in the Bi-Sn solder bumps on $Au(0.1{\mu}m)/Ni/Ti$ UBM and they were indentified as $(Au_xBi_yNi_{1-x-y})Sn_2$ Phase. The intermetallic compounds grown from the $Au(0.1{\mu}m)/Ni/Ti$ UBMinterface were dispersed in the solder bump.

• Journal of Surface Science and Engineering
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• v.9 no.2
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• pp.1-7
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• 1976

The dissolving and growth kinetics of intermetallic compounds for the reaction between solid iron and molten zinc were studied under nitorgen atmosphere over the temperature range between470$^{\circ}C$ and 680$^{\circ}C$. The rates of dissolution of solid iron into molten zinc were obtained under a static conditon, The amount of dissolution of sold iron and the growth of intermetalic compounds could be determined by means of microscopy. The thickness of intermetallic compound at a given temperature increases with increasing time, whereas for a given time decreases with increasing temperature . The rate of dissolution is controlled by the diffusion process of iron in the effective boundary layer of molten zinc over the temperature range 470$^{\circ}$-530$^{\circ}C$, 570$^{\circ}$-620$^{\circ}C$, and 650$^{\circ}$-665$^{\circ}C$, while by the surface reaction over the range 530$^{\circ}$-570$^{\circ}C$ and 620$^{\circ}$-650$^{\circ}C$.