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질소 이온 주입시킨 7050Al 합금의 표면 미세구조 변화와 저주기 피로거동
이창우,권숙인 ( C . W . Lee,S . I . kwun ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.4
The surface microstructure modification by N^+ ion implantation into 7050Al alloy and its low cycle fatigue behavior were investigated. Ion implantation method is to physically implant accelerated ions to the surface of a substrate. High dose of nitrogen(5×10^(17)ions/㎠) were implanted into 7050Al alloy using current density of accellerating voltage of 100KeV. The implanted layers were characterized by Electron Probe-Micro Analysis(EPMA), Auger Elecron Spectroscopy(AES), X-Ray Diffraction(XRD), X-Ray Photoelectron Spectroscopy(XPS), and Transmission Electron Microscopy(TEM). The experimental results were compared with computer simulation data. It was shown that AlN was formed to 4500Å deep. The low cycle fatigue life of the N^+ ion modified material was prolonged by about three times the unimplanted one. The improved low cycle fatigue life was attributed to the formation of AIN and the damaged region on the surface by N^+ ion implantation.
기계적합금화로 제조된 Ni-20Cr-20Fe-5Nb 합금에서 PCA로서 H<sub>2</sub>O의 역할과 시효석출거동
김일호,권숙인,이원식,채수원,황선근,김명호,Kim Il-Ho,Kwun S.I.,Lee Won-Sik,Chae S.W.,Hwang S.K.,Kim M.H. 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.3
The effect of use of $H_2O$ as PCA(process control agent) to prevent the carbon contamination during mechanical alloying process and the precipitation behavior in Ni-20Cr-20Fe-5Nb bulk alloy after aging were investigated. NbC and $Cr_2O_3$ were formed during mechanical alloying and consolidation processes in the Ni-20Cr-20Fe-5Nb alloy in which methanol($CH_3OH$) was added as PCA. Formation of NbC in this alloy decreased the amount of Nb dissolved in the Ni matrix. The use of $H_2O$ as PCA in Ni-20Cr-20Fe-5Nb alloy prevented the formation of NbC and increased the hardness. The increase of hardness in this alloy was attributed to the increased amount of Nb dissolved in the Ni matrix. After aging treatment for 20 hours at $600^{\circ}C\;and\;720^{\circ}C$ of Ni-20Cr-20Fe-5Nb bulk alloy in which $H_2O$ added as PCA, ${\gamma}"$$(Ni_3Nb,\;tetragonal)\;and\;{\delta}\;(Ni_3Nb,\;orthorhombic)$ precipitates were formed, respectively. The precipitation temperatures of ${\gamma}"$ and ${\delta}$ in this bulk alloy were lower than those in commercial IN 718 alloy. It seemed that the lower precipitation temperatures for ${\gamma}"$ and ${\delta}$ in this bulk alloy than in commercial IN 718 alloy were due to severe plastic deformation during mechanical alloying.
초내열합금 wide-gap 브레이징부의 미세조직 및 기계적 성질 변화에 미치는 첨가금속분말의 영향
김용환,권숙인,변재원,이원식,Kim Y. H.,Kwun S. I.,Byeon J. W.,Lee W. S. 한국재료학회 2005 한국재료학회지 Vol.15 No.6
The effect of IN738 additive powder on microstructure and mechanical properties of the wide-gap region brazed with BNi-3 filler metal powder was investigated. The wide-gap brazing was conducted in a vacuum of $2\times10^{-5}torr\;at\;1200^{\circ}C$ with various powder mixing ratios of additive to filler powders. The microstructures of the wide-gap brazed region were analyzed by SEM and AES. The region brazed with only BNi-3 filler metal powder had a microstructure consisted of proeutectic, binary eutectic and ternary eutectic structure, while that brazed with a mixture of IN738 additive powder and BNi-3 filler metal powder had a microstructure consisted of IN738 additive powder, binary eutectic of $Ni_3B-Ni$ solid solution and (Cr, W)B. The fracture strength of the wide-gap brazed region was about 680 MPa regardless of the additive powder mixing ratios. Cracks were initiated at the (Cr, W)B and binary eutectic of $Ni_3B-Ni$ solid solution, and propagated through them in the wide-gap brazed region, which lowered the fracture strength of the region.
기계적합금화로 제조된 Al - 4Mg 기 합금의 고온 기계적성질
이용각,전채홍,권숙인,연윤모 ( Yong Gak Lee,Chae Hong Jeon,S . I . Kwun,Yun Mo Yeon ) 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.3
N/A The mechanical properties of mechanically alloyed Al-4wt%Mg alloys dispersed with MgAl₂O₄dispersoilds at room and elevated temperatures were investigated. The powders in steady state during mechanical alloying consisted of Mg-supersatu rated Al solid solution and Al₄C₃which resulted from the reaction of Al with C in process control agent (methanol). The hot-extruded materials consisted of uniformly dispersed fine MgAl₂O₄, γ-Al₂O₃, Al₂O₃ and matrix with extremly fine substructure. Tensile specimens prepared from the extruded bars were tested at rowan temperature to 400℃ under different strain rates. The tensile strength of alloys at room temperature ranged from 500 to 594㎫. At elevated temperatures, the tensile strengths and elongations decreased with increasing temperature. Adding 3% MgAl₂O₄to Al-4wt%Mg increased the tensile strength of 50㎫ at rowan temperature and 20㎫ at 400℃.
WC-Co-Cr 용사코팅시 분말의 혼합이 코팅층의 기계적 특성에 미치는 영향
이창우 ( Chang Woo Lee ),한준현 ( Jun Hyun Han ),신명철 ( Myung Chul Shin ),권숙인 ( S. I. Kwun ) 대한금속재료학회 ( 구 대한금속학회 ) 2009 대한금속·재료학회지 Vol.47 No.5
We report on the effects of mixing of powders with various particle sizes on fracture toughness and wear resistance of thermally sprayed WC-10Co-4Cr coating layers fabricated by HVOF (high-velocity oxygen fuel) process. The size and the mixing ratio of powders were changed in order to get high fracture toughness and wear resistance. The mixing of small amount of coarse powders with fine powders resulted in the highest fracture toughness and wear resistance due to the lowest porosity in coating layers. (Received November 1, 2008)