• 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.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.141-147
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• 2010

An Ni-Al intermetallic coating has been produced by induction heating on mild steel. The effect of the induction heating conditions on the microstructure of the coating has been investigated. The reaction synthesis of the intermetallic compounds was promoted while increasing the heating rate and the holding time at reaction temperature. Especially, an NiAl phase corresponding to the initial composition of mixed powder was predominantly formed. However, the synthesis at low reaction temperatures occurred by solid state diffusion during the holding time and an Fe-Al reaction layer was formed at the interface with the substrate, regardless of the heating rate. The combustion synthesis of the intermetallic compound occurred at a temperature higher than 1023 K and resulted in an almost single phase NiAl structure.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.04a
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• pp.23-23
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• 2001

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.19-19
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• 1997

• Journal of Powder Materials
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• v.21 no.5
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• pp.338-342
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• 2014

In the present work, we investigated the mechanical alloying of binary Ga-Se(1:1) and Ga-Te(1;1) sysyems. The high-energy ball-milling was performed at $40^{\circ}C$ where one of constituents (Ga) is molten state. The purpose of the work was to see whether reactions between constituent elements are accelerated by the presence of a liquid phase. During the ball-milling, the liquid Ga phase completely disappeared and the resulting powders consist of nanocrystalline grain of ~20 nm with partly amorphized phases. However, no intermetallic compounds formed in spite of the presence of the liquid phases which has much higher diffusivity than solid constituents. By subsequent heat-treatments, the intermetallic compounds such as GaSe and GaTe formed at relatively low temperatures. The formation temperature of theses compound was much lower than those predicted by equilibrium phase diagram. The comparison of the ball-milled powders with un-milled ones indicated that the easy formation of intermetallic compound or allying occurs at low temperatures.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.51-56
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• 2007

A $CO_2$ laser overlay was conducted by using a Fe-based powder on the AC2B aluminum substrate. Cracks and intermetallic compounds (IMC) were observed inconsistently along the interface between the overlay and post-molten layer. A scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) detected some Fe-rich IMC ($Fe_3Al$, FeAl) as well as the brittle Al-rich IMC ($Fe_2Al_5,\;FeAl_3$). Micro vickers hardness proved the formation of Al-rich IMC ($FeAl_3$) along the interface by showing HV0.1 $800{\sim}900$. Furthermore, nano indentation was successfully applied to investigate the behavior of IMC more precisely than the micro vickers hardness.

• Korean Journal of Metals and Materials
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• v.50 no.1
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• pp.28-33
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• 2012

Ball-milled Ni-Al powder compacts have been synthesized by the heat of molten cast iron and have been coated on cast iron. The effects of the ball-milling time on the microstructure of the intermetallic coatings have been investigated. The experimental results showed that the ball-milled Ni-Al powder compacts were completely reacted and were successfully coated on the cast iron without re-melting the substrate. Densification of the coating layers was enhanced by increasing the ball-milling time. This might be attributed to the fact that the heat released during the intermetallic reaction was dispersed over a prolonged reaction time by the ball-milling of the elemental powders.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.997-1004
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• 1995

Intermetallic compound NbAl₃and amorphous phases were synthesized by mechanical alloying of elemental powder mixtures of niobium and aluminum. The composition of the powder mixtures was Nb-45wt%Al(75at%Al). The mechanical alloying was performed with a high energy SPEX 8000 mixer/mill up to 72 hrs. The resulting powders were analyzed by XRD, DTA, SEM and TEM. The mechanically alloyed powders exhibited lamellar structures in the early stage. And the elements of Nb and Al were homogeneously distributed over the Powder when a steady state was reached. An intermetallic compound, NbAl₃, was formed by mechanical alloying for 4 hrs. The mechanically alloyed powders exhibited a large exotherm around 600℃, corresponding to formation of stable NbAl₃and stress relief.

• Journal of Powder Materials
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• v.26 no.4
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• pp.319-326
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• 2019

Additive manufacturing (AM) is a highly innovative method for joining dissimilar materials for industrial applications. In the present work, AM of STS630 and Ti-6Al-4V powder alloys on medium entropy alloys (MEAs) NiCrCo and NiCrCoMn is studied. The STS630 and Ti64 powders are deposited on the MEAs. Joint delamination and cracks are observed after the deposition of Ti64 on the MEAs, whereas the deposition of STS630 on the MEAs is successful, without any cracks and joint delamination. The microstructure around the fusion zone interface is characterized by scanning electron microscopy and X-ray diffraction. Intermetallic compounds are formed at the interfacial regions of MEA-Ti64 samples. In addition, Vicker's hardness value increased dramatically at the joint interface between MEAs and Ti-6Al-4V compared to that between MEAs and STS630. This result is attributed to the brittle nature of the joint, which can lead to a decrease in the joint strength.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1033-1034
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• 2006

Metallic compound of ternary Al-B-C system was prepared by mechanical alloying (MA) using Al, boron and graphite powders as starting materials. MA was carried out using Spex 8000 mixer/mill for 50 hours in an argon atmosphere without process control reagent such as methyl alcohol. The MA powders obtained were heat-treated in vacuum at the temperature of 873 and 1273 K for 5 hour. Pure ternary Al-B-C compound was obtained in the chemical content of Al:B:C=55:27:18. The ternary compound obtained in this study has a new phase whose crystal structure is not identified yet.