• 제목/요약/키워드: Ni-W alloy

검색결과 180건 처리시간 0.028초

NiCrCoW 계 단결정 주조블레이드의 미세구조 관찰 (Microstructural Observation on Single Crystal Cast Blade of NiCrCoW Alloy)

  • 안성욱;김수철;임옥동;서동이;;배영일;허무영
    • 한국재료학회지
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    • 제6권9호
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    • pp.871-877
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    • 1996
  • 가스터빈용 단결정 주조 블레이드는 기포 및 Freckle등과 같은 주조결함이 없어야 하며, 수지상, ${\gamma}$'크기와 모양에 따라 화학조성이 다르며, 기지와 공정조직을 각각 2영역 및 3영역으로 분류할 수 있었다. 또한, Ti는 첨가원소호서 조직제어에 매우 중요한 역할을 하였다.

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고밀도화 공정에 의한 Fe-Co 계 밸브시트 합금의 조직변화와 열적 특성 (Thermal Properties and Microstructural Changes of Fe-Co System Valve Seat Alloy by High Densification Process)

  • 안인섭;박동규;안광복;신승목
    • 한국분말재료학회지
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    • 제26권2호
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    • pp.112-118
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    • 2019
  • Infiltration is a popular technique used to produce valve seat rings and guides to create dense parts. In order to develop valve seat material with a good thermal conductivity and thermal expansion coefficient, Cu-infiltrated properties of sintered Fe-Co-M(M=Mo,Cr) alloy systems are studied. It is shown that the copper network that forms inside the steel alloy skeleton during infiltration enhances the thermal conductivity and thermal expansion coefficient of the steel alloy composite. The hard phase of the CoMoCr and the network precipitated FeCrC phase are distributed homogeneously as the infiltrated Cu phase increases. The increase in hardness of the alloy composite due to the increase of the Co, Ni, Cr, and Cu contents in Fe matrix by the infiltrated Cu amount increases. Using infiltration, the thermal conductivity and thermal expansion coefficient were increased to 29.5 W/mK and $15.9um/m^{\circ}C$, respectively, for tempered alloy composite.

Study on the Performance of Laser Welded joint of Aluminum alloys for Car Body

  • Kutsuna, Muneharu;Kitamura, Shuhei;Shibata, Kimihiro;Salamoto, Hiroki;Tsushima, Kenji
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.620-625
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    • 2002
  • Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6N01 alloy welds. Aluminum alloy plate of 2.0mm in thickness with filler metal bar was welded by twin beam Nd:YAG laser facility (total power:5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 l/min was used. The defocusing distance is kept at 0 mm. At travel speeds of 3 to 9 m/min and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

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Study on the Performance of Laser Welded Joint of Aluminum Alloys for Car Body

  • Kutsuna, M.;Kitamura, S.;Shibata, K.;Sakamoto, H.;Tsushima, K.
    • International Journal of Korean Welding Society
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    • 제2권2호
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    • pp.26-31
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    • 2002
  • Considering the fuel consumption of car, a light structure of aluminum alloys is desired fer car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. In the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6NO 1 alloy welds. Aluminum alloy plate of 2.Omm in thickness with filler metal bar was welded by twin beam Nd: YAG laser facility (total power: 5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 1/min was used. The defocusing distance is kept at 0 mm. At travel speeds off 3 to 9 and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

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열간압연 된 Fe55Co17.5Ni10Cr12.5Mo5 고엔트로피합금의 소둔 조건에 따른 기계적 특성 변화 (Annealing Effect on the Mechanical Properties of Hot-Rolled Fe55Co17.5Ni10Cr12.5Mo5 High-Entropy Alloy)

  • 박해돈;배동화;원종우;문종언;김형섭;설재복;성효경;배재웅;김정기
    • 소성∙가공
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    • 제31권5호
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    • pp.273-280
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    • 2022
  • Although the mechanical properties of high-entropy alloys depend on the annealing conditions, limited works were established to investigate the annealing effect on the mechanical properties of Mo-added high-entropy alloys. Therefore, in the present work, the annealing effects on the microstructural evolution and mechanical properties of Mo-added high-entropy alloy were investigated. As a result, incomplete recrystallization from the limited annealing time not only suppresses deformation-induced phase transformation during cryogenic tensile test but also induces a deformation instability that results into the ductility reduction compare with the fully recrystallized sample. This result represents adjustment of annealing time is useful to control both transformation-induce plasticity and deformation instability of high-entropy alloys, and this can be applied to control the mechanical properties of metallic alloys by combining pre-straining and subsequent annealing.

정밀주조 Hastelloy C-276 합금의 미세조직과 기계적 성질에 미치는 W 함량과 열처리의 영향 (Effect of Tungsten Contents and Heat Treatment on the Microstructures and Mechanical Properties of Hastelloy C-276 Alloy Investment Castings)

  • 유병기;박흥일;배차헌;김성규;정해용
    • 한국주조공학회지
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    • 제37권1호
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    • pp.21-29
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    • 2017
  • 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 Ni-based 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 ${\mu}$ 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.

화염급냉 표면처리된 Cu-8.8Al-4.5Ni-4.5Fe 합금의 미세구조 분석 및 내마모성에 관한 연구 (Characterization of the Microstructure and the Wear Resistance of the Flame-Quenched Cu-8.8Al-4.5Ni-4.5Fe Alloy)

  • 이민구;홍성모;김광호;김경호;김흥회
    • 열처리공학회지
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    • 제17권6호
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    • pp.346-355
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    • 2004
  • The flame quenching process has been employed to modify the surfaces of commercial marine propeller material, aluminum bronze alloy (Cu-8.8Al-5Ni-5Fe), and the microstructure, hardness and wear properties of the flame-quenched layers have been studied. The thermal history was accurately monitored during the process with respect to both the designed maximum surface temperature and holding time. The XRD and EDX analyses have shown that at temperatures above $T_{\beta}$, the microstructure consisting of ${\alpha}+{\kappa}$ phases changed into the ${\alpha}+{\beta}^{\prime}$ martensite due to an eutectoid reaction of ${\alpha}+{\kappa}{\rightarrow}{\beta}$ and a martensitic transformation of ${\beta}{\rightarrow}{\beta}^{\prime}$. The ${\beta}^{\prime}$ martensite phase formed showed a face-centered cubic (FCC) crystal structure with the typical twinned structure. The hardness of the flame-quenched layer having the ${\alpha}+{\beta}^{\prime}$ structure was similar to that of the ${\alpha}+{\kappa}$ structure and depended sensitively on the size and distribution of hard ${\kappa}$ and ${\beta}^{\prime}$ phases with depth from the surface. As a result of the sliding wear test, the wear resistance of the flame-quenched layer was markedly enhanced with the formation of the ${\beta}^{\prime}$ martensite.

형상기억합금을 이용한 회전공구 클램핑 장치 구현 (Implementation of the rotating tool clamping device using a shape memory alloy)

  • 정준모;박종권;이동주;신우철
    • 한국공작기계학회논문집
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    • 제17권1호
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    • pp.16-20
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    • 2008
  • This paper presents the construction of micro tool clamping device using a Ni-Ti shape memory alloy(SMA) ring. Clamping force of the device is produced by elastic force of the SMA reverted to its original shape in normal temperature. Phase transformation of the SMA was realized by temperature control using a peltier element. Prototype of the SMA tool clamping device was fabricated and examined its clamping force and clamping/unclamping operation.

Ni-Cr계 합금을 이용한 박막저항의 제작 및 신뢰성 (Fabrication and Reliability Properties of Ni-Cr Alloy Thin Film Resistors)

  • 이봉주
    • 한국전기전자재료학회논문지
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    • 제21권1호
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    • pp.57-62
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    • 2008
  • From the progressing results, it was found that thin film using 52 wt% Ni - 38 wt% Cr - 3 wt% Al - 4 wt% Mn - 3 wt% Si target has good characteristics for low TCR (temperature coefficients of resistance) and high resistivity. The optimum sputtering condition was DC 250 W, 5 mtorr, and 50 sccm and the proper annealing condition was $350^{\circ}C$/3.5 hr in air atmosphere. At these fabricated conditions, thin film resistors with TCR values of less than ${\pm}10ppm/^{\circ}C$ were obtained. The TCR of the packaged-samples made at proper fabrication conditions was $-3{\sim}15ppm/^{\circ}C$ after the thermal cycling and $-20{\sim}180ppm/^{\circ}C$ after PCT (pressure cooker test), we could confirm reliability for the thin film resistor and find the need for enduring research about packaging method.

Surface segregation of NiZr and CuZr alloys.

  • Kang, H.J.;Park, N.S.;Kim, M.W.;O'Conner, D.J.;Macdonald, R.J.
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1994년도 제6회 학술발표회 논문개요집
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    • pp.35-35
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    • 1994
  • The surface segragation of NiZr, CuZr alloy has been studied wi th X-ray Imotoelectron spectroscopy(XPS), Auger electron spectroscopy(AES) and low energy ion scattering(LEIS). The composition of outmost atomic layer has been determinded by the use of LEIS at several incident energies using Ar+ ion. In the LEIS analysis, the effect of charge exchange has been estimated by a novel measurment of the charge exchange parameters while simul taneous determining the relative concentrations of Ni and Zr and the complementary information obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted wi th the surface concentration of the preferentially sputtered surface. The experimental results has been clearly demonstrated that when the NiZr ruld CuZr alloys are exposed to continuous Ar+ ion bombardment the outermost atomic layer is Zr rich due to preferential sputtering of Ni atoms. where Ni is preferentially sputtered, but the difference in sputtering yields is not sufficient to explain the observed composition. Therefore, it is necessary to consider other processes such as Radiation Induced Segregation(RIS). The surface composition of the heated sample surface predicts that Zr should surface segregate which futher supports the view that part of the Zr enrichment is due to RIS.to RIS.

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