• Title/Summary/Keyword: Liquid formability

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Evaluation on Liquid Formability of Bulk Amorphous Alloys (벌크비정질합금의 액상 성형성 평가)

  • Joo, Hye-Sook;Kang, Bok-Hyun;Kim, Ki-Young
    • Journal of Korea Foundry Society
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    • v.26 no.5
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    • pp.227-231
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    • 2006
  • Liquid formability of bulk amorphous alloys is known to be very poor due to their high viscosity comparing with conventional metallic materials. It is important to have the fabricating technology of bulk amorphous alloys in order to make the components with complicated shape. Liquid formability includes the mold cavity filling ability and the hot tear(crack) resistance during solidification. A mold made of a commercial tool steel for the formability test was designed. Melting was performed by the arc melting furnace with melting capacity of 200 g in an argon atmosphere. Liquid formability and glass forming ability of Cu base and Ni base bulk amorphous alloys were measured and evaluated. Mold filling ability of Ni-Zr-Ti-Si-Sn alloy was better than that of Cu-Ni-Zr-Ti alloy, however the reverse is the hot tear resistance. Bulk amorphous alloy is very susceptible to crack if partial crystallization occurs during solidification. Crack resistance was thought to be closely related with the glass forming ability.

Optimum Combination of Thermoplastic Formability and Electrical Conductivity in Al-Ni-Y Metallic Glass

  • Na, Min Young;Park, Sung Hyun;Kim, Kang Cheol;Kim, Won Tae;Kim, Do Hyang
    • Metals and materials international
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    • v.24 no.6
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    • pp.1256-1261
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    • 2018
  • Both thermoplastic formability and electrical conductivity of Al-Ni-Y metallic glass with 12 different compositions have been investigated in the present study with an aim to apply as a functional material, i.e. as a binder of Ag powders in Ag paste for silicon solar cell. The thermoplastic formability is basically influenced by thermal stability and fragility of supercooled liquid which can be reflected by the temperature range for the supercooled liquid region (${\Delta}T_x$) and the difference in specific heat between the frozen glass state and the supercooled liquid state (${\Delta}C_p$). The measured ${\Delta}T_x$ and ${\Delta}C_p$ values show a strong composition dependence. However, the composition showing the highest ${\Delta}T_x$ and ${\Delta}C_p$ does not correspond to the composition with the highest amount of Ni and Y. It is considered that higher ${\Delta}T_x$ and ${\Delta}C_p$ may be related to enhancement of icosahedral SRO near $T_g$ during cooling. On the other hand, electrical resistivity varies with the change of Al contents as well as with the change of the volume fraction of each phase after crystallization. The composition range with the optimum combination of thermoplastic formability and electrical conductivity in Al-Ni-Y system located inside the composition triangle whose vertices compositions are $Al_{87}Ni_3Y_{10}$, $Al_{85}Ni_5Y_{10}$, and $Al_{86}Ni_5Y_9$.

A study on the micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ Bulk Metallic Glasses using micro-forging and Finite Element Method applications (마이크로 단조를 이용한 Zr 계 벌크 비정질합금의 미세 성형성 평가와 유한요소해석 적용에 관한 연구)

  • Kang Sung-Gyu;Park Kyu-Yeol;Son Seon-Cheon;Lee Jong-Hon;Na Young-Sang
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.153-161
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    • 2006
  • Micro-forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Micro-forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, micro- formability of a representative bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$. was investigated for micro-forging of U-shape pattern. Micro-formability was estimated by comparing $R_f$ values ($=A_f/A_g$), where $A_g$ is cross-sectional area of U groove, and $A_f$ the filled area by material. Micro-forging process was simulated and analyzed by applying finite element method. FEM simulation results showed reasonable agreement with the experimental results when the material properties and simulation conditions such as top die speed, remeshing criteria and boundary conditions were tightly controlled. The micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ was increased with increasing load and time in the temperature range of the supercooled liquid state. Also, FEM simulation using a commercial software, DEFORM was confirmed to be applicable for the optimization of micro-forming process.

A study on the micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk metallic glass using micro-forging and finite element method application (Zr 계 벌크비정질합금의 마이크로 단조를 이용한 미세 성형성 평가와 유한요소해석 적용에 관한 연구)

  • Kang S.G.;Na Y.S.;Park K.Y.;Son S.C.;Lee J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.589-592
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    • 2005
  • Micro-forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Micro-forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, micro-formability of a representative bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated for micro-forging of U-shape pattern. Micro-formability was estimated by comparing $R_f$ values $(=A_f/A_g)$, where Ag is cross-sectional area of U groove, and $A_f$ the filled area by material. Microforging process was simulated and analyzed by applying finite element method. FEM simulation results should reasonable agreement with the experimental results when the material properties and simulation conditions such as top die speed, remeshing criteria and boundary conditions tightly controlled. The micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ was increased with increasing load and time in the temperature range of the supercooled liquid state. Also, FEM Simulation using DEFORM was confirmed to be applicable for the micro-forming process simulation.

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Room and High Temperature Deformation Behaviors and Estimation on Formability of Zr-based Bulk Metallic Glass Composite (Zr-Nb-Cu-Ni-Al 비정질 복합 재료의 변형거동과 성형성)

  • Jun, H.J.;Lee, K.S.;Kuhn, U.;Eckert, J.;Chang, Y.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.199-202
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    • 2008
  • In this study, we investigated the thermal properties of $Zr_{66.4}Nb_{6.4}Cu_{10.5}Ni_{8.7}Al_{8.0}$ by using a differential scanning calorimeter (DSC), and then analyzed the composition of dendrite phase by using X-ray diffraction (XRD). A series of uniaxial compression tests has been performed under the strain rates between $10^{-5}/s$ and $10^{-2}/s$ at room temperature and near SLR. This BMGC has higher high temperature strength than other Zr-based monolithic BMGs because in-situ formed crystalline phases hinder a feasible viscous flow of amorphous matrix. Warm formability is also estimated by laboratory-scale extrusion test within supercooled liquid region. It was found that BMGC has poor formability compared with nother Zr-based bulk metallic glass composite presumably due to large volume fraction of 'brittle' crystalline phases distributed within amorphous matrix.

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A study on electrical and mechanical properties and press formability of a Cu/Ag composite sheet (Cu/Ag 복합판재의 전기/기계적 성질 및 프레스 성형성에 관한 연구)

  • Shin, Je-Sik
    • Design & Manufacturing
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    • v.6 no.1
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    • pp.95-100
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    • 2012
  • In this study, a novel Cu composite sheet with embedded high electric conduction path was developed as another alternative for the interconnect materials possessing high electrical conductivity as well as high strength. The Cu composite sheet was fabricated by forming Ag conduction paths not within the interior but on the surface of a high strength Cu substrate by damascene electroplating process. As a result, the electrical conductivity increased by 40% thanks to mesh type Ag conduction paths, while the ultimate tensile strength decreased by 20%. The interfacial fracture resistance of Cu composite sheet prepared by damascene electroplating increased by above 50 times compared to Cu composite sheet by conventional electroplating. For feasibility test for practical application, a leadframe for LED module was manufactured by a progressive blanking and piercing processes, and the blanked surface profile was evaluated as a function of the volume fraction of Ag conduction paths. As Ag conduction path became finer, pressing formability improved.

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Semi-Solid Forming Process of Thin Products (박막 성형품의 반응고 성형공정)

  • 서판기;정용식;강충길
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.60-63
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    • 2003
  • Semi-solid forming is the process of stirring alloy during solidification, making the mixture of liquid and solid, solidifying it, reheating it to the solid-liquid coexistent temperature, and then injecting this semi solid slurry into dies. In the semi-solid die casting process, it is very important to find out the correlation of injection condition, microstructure and mechanical properties. Especially, an improper injection condition is the main cause of liquid segregation and non-homogeneous mechanical properties due to the difference of solid fraction according to the position of the products. To ensure the database requisite to the semi-solid die casting product, it is essential to acquire the mechanical properties considering liquid segregation to the injection condition. In this study, the effect of injection condition on liquid segregation, formability, microstructure and mechanical properties in a thin product was investigated.

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A Study on the Micro Vibration Forming of Al-based Superplastic Alloy and Zr-based Bulk Metallic Glass (Al계 초소성합금과 Zr계 비정질합금의 마이크로 진동성형에 관한 연구)

  • Son, Seon-Cheon;Park, Kyu-Yeol;Na, Young-Sang
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.6
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    • pp.193-200
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    • 2007
  • Micro forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load effect to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG).

Fabrication of Ni-Nb-Ti-Zr Amorphous Alloys with Wide Supercooled Liquid Region (넓은 과냉각 액체영역을 가지는 Ni-Nb-Ti-Zr계 비정질 합금의 제조)

  • Kim, Sung-Gyoo
    • Journal of Korea Foundry Society
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    • v.22 no.5
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    • pp.252-256
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    • 2002
  • Ni-Nb-Ti-Zr amorphous alloys were manufactured using melt-spinning methods. Amorphous formability, the supercooled liquid region before crystallization and mechanical properties were examined. The value of the reduced glass transition temperature and the supercooled liquid region of $Ni_{62}Nb_{10}Ti_{13}Zr_{15}$ alloy were relatively high and were 0.612 and 76 K respectively. However, amorphous bulk alloy rod was not formed using the Cu-mold die casting. The mechanical properties were in the range of $800{\sim}900DPN$ of hardness and $2.5{\sim}2.8$ GPa of tensile strength in the whole composition range.

A Study on the Relationship between Deformation Mode and Extrusion Properties for Zr-based Bulk Metallic Glass (Zr계 벌크 비정질 합금의 변형 모드와 압출 특성의 상관 관계에 관한 연구)

  • Lee K. S.;Chang Y. W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.10a
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    • pp.199-202
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    • 2004
  • In this present study, an attempt was made to determine the deformation mode of the Zr-Ti-Cu-Ni-Be bulk metallic glass by compression test over a wide range of temperatures and strain rates. From the results, empirical deformation map could be constructed including the boundaries of different deformation modes. Considering power dissipation map and instability map developed on the basis of the Dynamic Materials Model (DMM), the processing map for extrusion could also be constructed. In addition, the macroscopic formability of this BMG alloy has also been examined through the extrusion in laboratory scale within undercooled liquid state. From the results of macroscopic extrusion formability, both deformation map and processing map present good criteria to determine optimal forming conditions.

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