• 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.

• Korean Journal of Materials Research
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• v.5 no.3
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• pp.345-356
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• 1995

본 연구에서는 TiAl 금속간 화합물을 자전 고온 반응법을 이용하여 제조시 반응과정을 열시차 분석 방법으로 분석하였다. 합금 조성은 Ti-45at% Al, 53at%Al, 알루미늄 분말 크기, 승온 속도, 성형 밀도 등을 변화시켜 이들이 반응 과정에 미치는 영향을 관찰하였다. 분말이 미세할수록, 승온속도가 느릴수록, 성형 밀도가 낮을수록 반응 점화 온도 및 연소 온도가 감소하였으며, 고상 Ti와 고상 Al간의 반응정도가 증가하는 것이 관찰되었다. 고상 Ti와 고상 Al간의 반응에서 생성되는 것은 XRD 분석 결과 Ti$Al_{3}$상으로 확인되었다. 이에 비하여 반응 점화 온도가 알루미늄의 용융 온도보가 높을 경우에는 생성되는 상이 $Ti_{3}$Al, TiAl상으로 확인되었다. 이러한 상의 생성 원인에 대하여 확산 계수 및 알루미늄의 용해도등의 요인으로 설명하였다.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.987-992
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• 1998

Titanium aluminide intermetallic compound was formed from high purity elemental Ti and A1 foils by selfpropagating, high-temperature synthesis(SHS1 in hot press. Formation of $TiAl_3$ intermetallics at the interface between Ti and Al foil was observed to be controlled by temperature, pressure and heating rate. Especially, the heating rate is the most important role to form intermetallic compound by SHS reaction. According to DTA experiment, the SHS reactions appeared at two different temperatures below and above the melting point of Al. It was also observed that both SHS reaction temperatures increased with increasing the heating rate. After the SHS reaction of alternatively layered 10 Ti and 9 A1 foils at the heating rate of $20^{\circ}C$/min, the $700\mu\textrm{m}$ thick titanium aluminide sheet was formed by heat treatment at $810^{\circ}C$ for 4hours.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.113-113
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• 1999

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.5-5
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• 1994

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.164-170
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• 2001

The Self-propagating High-temperature Synthesis (SHS) for synthesizing ($Mo_{1-z}$ , $W_{z}$)$Si_2$was conducted experimentally with the mole fraction of Tungsten(W) from z=0.0 to z=0.5. The temperature profile was measured according to the reaction time through the thermocouple that was equipped into the center of these samples. When the reaction front is propagated around the thermocouple, the highest temperature appears and we regard this temperature as the adiabatic temperature. We found out by experimental results that the reaction velocity is in the range of 2.14~1.35mm/sec and the adiabatic temperature is in the range of 1883~1507K for the six samples. The reaction velocity and the adiabatic temperature were inclined to decrease with an increasing of the mole fraction of Tungsten (W). The SHS modeling is presented in order to predict the temperature profiles and these results are compared with the experimental results. It is predicted that in case of increasing the initial temperature of these six samples, the reaction temperature increased and that the sample of z=0.5 needs the preheating up to 800~900K in order to become reaction temperature 1900K.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.573-580
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• 1998

Self-propagating high temperature synthesis (SHS) technique was used to synthesize the spinel phase of $MgAl_2O_4$ from MgO and Al powder. Thermit reaction products of MgO and Al, The reaction products were heat treated at the temperature $800^{\circ}C$ preheating. Processing factors such as DTA/TG, combustium product and maxium temperature, synthesis of MgO and Al from "$MgO+2Al+3/2O_2$\rightarrow$MgAl_2O_4$". An activation energy (${\Delta}H^{\circ}$)-264.8 kcal/mol and reaction of maxium temperature 5634 K was calculated to form a $MgAl_2O_4$ spinel from unreacted materials. Pellet were increased volume 6% after thermit reaction. reaction.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.120-127
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• 1998

The finite element method has been used to model and analyze the heat transfer phenomena during manufacturing process of $MoSi_2$ by SHS(Self-propagating High-temperature Synthesis). For this purpose nonlinear transient heat transfer analyses by using ANSYS have been performed to estimate the temperature distributions and the peak temperature in the test specimen. The effects of manufacturing process parameters such as pre-heating temperatures, the velocity of reaction zone have been investigated. The results of the analysis have been compared with the experimental results.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.12-13
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.14-15
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• 1998