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고에너지 전자빔투사방법에 의해 제조된 TiB2 표면합금화 재료의 미세조직 연구
신기삼,어광준,이성학 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.5
The present study is concerned with the processing and the microstructural analysis of surface alloyed materials with TiB₂ powders using irradiation of high-energy electron beam. The mixtures of TiB₂ powders and flux were deposited on a plain carbon steel plate, and then electron beam was irradiated on these mixtures using an electron beam accelerator. The microstructures of the irradiated surface layers were examined by optical and scanning electron microscopy. A few residual micropores were found in the sample processed without flux, but their number was decreased in the samples processed with a considerable amount of flux. As a result of irradiation, the Ti content was homogeneously maintained throughout the melted region, whose hardness was greatly improved. This was associated mainly with the microstructural modification including the segregation of Ti and B along solidification cell boundaries and the formation of fine Ti(C,M) particles.
$2XXX Al-SiC_w$ 복합재료의 분말야금 제조와 기계적 성질 향상 연구
신기삼 한국분말야금학회 1995 한국분말재료학회지 (KPMI) Vol.2 No.3
The purpose of this study is to establish powder metallurgy (P/M) fabrication processes for high performance 2XXX Al composites reinforced with SiC whiskers. Rapidly solidified 2XXX Al powders produced by commercial atomization technique were mixed with SiC whiskers. The results of mixing processes indicated that fluidized zone mixing technique was considerably effective for the large scale production of the mixture of Al powders and whiskers. In order to consolidate these $Al-SiC_w$ mixtures into $Al-SiC_w$ composite billets, a vacuum hot press was set up, and hot processing variables were investigated. Using the hot pressing temperature of $620^{\circ}C$ under the pressure of 50 MPa, good quality $Al-SiC_w$ composite billets having relatively homogeneous microstructure and sound Al/sic interfacial bonding were obtained. Composite billets were then extruded to bars having relatively homogeneous microstructures at the extrusion temperature of 450~500$^{\circ}C$ under the extrusion pressure of 700~ 1000 MPa. Mechanical properties of the extruded bars were found to be comparable with those of the composite processed by Advanced Composite Materials Corp. To improve mechanical properties of the composites, elimination of coarse intermetallic compounds, uniform distribution of reinforcements, and minimization of whisker breakage are suggested.
Cavity Formation Mechanism in Inert-Gas-Atomized Superalloy A-286
Shin, Keesam 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-
Cavity formation mechanism is that of great interest for the possibility of utilizing the cavities as a material strengthening elements and also for the application of the knowledge obtained to suppress the cavity formation upon radiation damage. In this study, the cavity formation mechanism is studied in the inert-gas-atomized superalloy A-286. The powders produced by IGA are rapidly solidified by the rapid heat extraction during atomization. This study focuses the effect solute atoms on the cavity formation.
Tailoring of Optoelectronic Properties of InAs/GaAs Quantum Dot Nanosystems by Strain Control
이웅,신기삼,명재민 대한금속·재료학회 2009 ELECTRONIC MATERIALS LETTERS Vol.5 No.4
Full three-dimensional numerical analysis based on continuum elasticity and model solid theory has been carried out to evaluate some possible means of tailoring the optoelectronic properties of InAs/GaAs quantum dot (QD) nanosystems. Numerical results predicted that while the stacking period control leads to the shifts in valence band edges, incorporation of InxGa1-xAs ternary strain relief layer (SRL) causes composition-dependent shifts in conduction band edges. On the other hand, modification of the SRL shape itself did not yield significant changes in the confinement potentials. It is therefore suggested that strain control by incorporation of ternary intermediate layers combined with geometry controls, would allow greater flexibility in the tailoring of the opto-electronic characteristics of QD-based systems.