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급냉응고된 Al-Li-X(=Ti , Zr) 합금의 석출거동에 관한 연구
정해용,배차헌,김인배,박세윤 ( Hae Yong Jeong,Cha Hurn Bae,In Bae Kim,Se Yun Park ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.2
N/A The Precipitation behavior of Al-Li-X(=Ti, Zr) alloys produced by a rapid solidification process and heat treated in the temperature range of 160℃ to 240℃ was investigated. The solid solubilty If Li atoms was shown to extend to 4.95w/o. The discontinuous precipitation reaction resulted from the preferential growth of δ´ phase. Also, the driving force of the growth was depend on the fluctuations of solute concentration. The coarsening rate of δ´phase followed a (time)^(⅓) dependency obeys the MLSW theory. The addition of Ti or Zr had a little effects on the formation amount better than the growth rate of δ´phase.
분사주조공정에 의하여 제조된 Al-Pb 과편정합금의 조직특성
배차헌,정해용,박흥일,김창업,이성렬 ( Cha Hurn Bae,Hae Young Jeong,Heung Il Park,Chang Up Kim,Sung Ryeol Lee ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.4
N/A In Al-Pb monotectic alloys Pb particles are difficult to uniformly distribute over the Al matrix because of the gravity segregation of pb element. Therefore the effects of centrifugally spray casting process on microstructures and distributions of Pb particle were investigated. As the preform thickened the sine of Pb particle became larger, the amount of porosity became lower and microstructures showed the change from spray-deposition microstructures in the lower part of the preform to spray-casting microstructures in the upper part of it. The size of Pb particles, amount of porosity and splat layer boundaries in hot forged preform showed still less than of as-deposited preform
화학조성 및 열처리경로 변화에 따른 Nimonic 80A 합금의 특성
최병강,정해용,배차헌,Choi Byong-Kang,Jeong Hae-Yong,Bae Cha-Hurn 한국재료학회 2005 한국재료학회지 Vol.15 No.12
Properties of Ni-base superalloys of Nimonic 80A alloy system were investigated by the observation of microstructures, precipitates ana hardness as a function of the chemical compositions ana the paths of heat treatment. The higher hardness values showed, the higher Ti/Al ratio among high compositions of Cr and Co element. The lower (Ti+Al) and Fe contents decreased in the same Ti/Al ratio, the higher hardness values showed. This results are considered that coherent deformation was increased with increasing Ti/Al ratio. Hardness showed higher value when Cr contents was $18 wt\%$ less than $21wt\%Cr$. In $3.15 wt\%$Co alloy, $\gamma'$ phase was very fine as around 50nm and, its volume fraction and hardness showed the highest value by 2step-aging treatment.
원심분사주조법에 의한 Cu-X(=Al2O3 , W)p 복합재료의 미세조직 및 복합화
배차헌,정해용 ( Cha Hurn Bae,Gae Yong Jeong ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.5
N/A Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles(Al₂O₃<40 )㎛, W<17.3 ㎛) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The Cu/W_P powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the Al₂O, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and Al₂O, particle is maximum. The microstructure of the Cu/W_P and the Cu/(Al₂O,)_P composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure,respectively. (Received July 24, 1997)
분사주조에 의한 입자강화 금속기지 복합재료의 제조시 액적의 열적거동과 미세조직에 대한 고찰
김명호,배차헌,정해용,박흥일 ( Myung Ho Kim,Cha Hurn Bae,Hae Young Jeong,Heung Il Park ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.4
N/A Particle-reinforced metal matrix composites via the Osprey spray casting process were fabricated by injecting second phase particles of Al₂O₃(<40㎛) and W(6㎛) into the spray of Cu droplets, and the thermal behaviors of the composite droplets during flight were considered theoretically on the basis of mixing modes between the Cu droplets and the reinforced particulates injected. It was found that the W-injected spray is comprised of particle-embedded droplets, and the Al₂O₃-injected spray comprises particle-attached droplets. From the predicted results of the thermal behaviors of the composite droplets and preforms produced, it is concluded that the thermal behaviors of the composite droplets during flight, and during the subsequent deposition are strongly influenced by its mixing modes between the reinforced particulates and Cu droplets during flight.
AZ31B 마그네슘 합금의 기계적 특성에 미치는 열간압출의 영향
김용길,최학규,강민철,정해용,배차헌,Kim Yong-Gil,Choi Hak-Kyu,Kang Min-Cheol,Jeong Hae-Yong,Bae Cha-Hurn 한국재료학회 2005 한국재료학회지 Vol.15 No.1
The microstructural changes by hot extrusion of AZ31B magnesium alloy were observed, and the relation to the tensile property was examined. The tensile properties as oriented longitudinal(L), half transverse(HT) and long transverse(LT) to the extrusion direction were investigated at $20^{\circ}C,\;100^{\circ}C,\;200^{\circ}C,\;300^{\circ}C\;and\;400^{\circ}C$, respectively. As the results, many recrystallized small grains distributed uniformly in large banded microstructures formed along the extrusion direction. The grain size of as-extruded specimen was around $30\~150\;{\mu}m$. As increasing the test temperature the tensile and yield strength with respect to the angle between the axis of the tensile and the longitudinal direction in extrusion was decreased, but their elongation were increased and their deviation between L and LT specimens have disappeared from $300^{\circ}C$. This mechanical anisotropy was reduced at elevated temperatures and almost disappeared at $400^{\circ}C$. It was considered that the homogenization was occured by the recrystallization and the change of slip system was occurred during tensile test process in elevated temperatures.
헬륨가스분사법으로 제조된 Al86Ni6Ce4Mg4 비정질합금 분말과 성형재의 특성
배차헌,김성규,이병우,박흥일,정해용 ( Cha Hurn Bae,Sung Gyoo Kim,Byung Woo Lee,Heung Il Park,Hae Yong Jeong ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.2
N/A ]Properties of Al_(86)Ni_6Ce₄Mg₄, alloy powder produced by helium gas atomization process were investigated by using DSC, XRD, SEM and TEM. The powders below 32㎛ in diameter were identified as an amorphous phase mixed with a α-Al phase. Al_(86)Ni_6Ce₄Mg₄, bulk alloy was manufactured by hot extruding the alloy powders at various temperatures, and the estimation of its mechanical properties was carried out subsequently. As a result, the bulk alloy extruded at the temperature below 450℃ exhibited the microstructure in which the near-spherical shape of some powders below 20㎛ were nearly unchanged and fine voids between matrix and powders were formed during extrusion process. On the other hand, the tensile strength and elongation at room temperature for Al_(86)Ni_6Ce₄Mg₄, bulk alloy extruded at 450℃ were 750㎫ and 7.5%, respectively.
정밀주조 Hastelloy C-276 합금의 미세조직과 기계적 성질에 미치는 W 함량과 열처리의 영향
유병기 ( Byung-ki Yoo ),박흥일 ( Heung-il Park ),배차헌 ( Cha-hurn Bae ),김성규 ( Sung-gyoo Kim ),정해용 ( Hae-yong Jeong ) 한국주조공학회 2017 한국주조공학회지 Vol.37 No.1
The effects of W content and heat treatment on the microstructure and mechanical properties of Hastelloy C-276 alloy investment castings were discussed. As the W content was increased, dendritic microstructure was refined and network type precipitate formed during solidification was distributed on the dendritic grain boundaries. Cr, Fe and Mn were highly segregated in the Nibased dendrite matrix, and Mo, W, C and Si were in the precipitates. Due to the heat treatment, fine granular and flake precipitates were newly formed in the matrix, and unresolved network type precipitates remained on the grain boundary. The network type precipitates and the granular and flake precipitates formed by heat treatment were confirmed to be μ phase intermetallic compounds with similar compositions. Due to the increase of the W content and the heat treatment, hardness and tensile strength were significantly increased. However, tensile strength after aging treatment was decreased with the W content. These results can be explained in that brittle fracturing by the unresolved network type precipitates dispersed in the grain boundary was predominant over ductile fracturing by the dimple ruptures originating from the fine granular precipitates in the matrix.