• Title/Summary/Keyword: amorphous alloy

Search Result 394, Processing Time 0.027 seconds

Deformation behavior in Cu-based bulk amorphous alloys composite during compression (동기지 동계 Bulk Amorphous 복합재의 압축 변형거동)

  • Lee C. H.;Kim J. S.;Park E. S.;Huh M. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2004.10a
    • /
    • pp.203-206
    • /
    • 2004
  • Copper-based bulk amorphous alloy composite was synthesized by using the copper-coated $Cu_{54}Ni_{6}Zr_{22}Ti_{18}$ amorphous powder which was obtained by argon gas atomization. The amorphous powder having a super-cooled liquid region of 53 K was coated by crystalline copper by electroless coating. The consolidation was carried out by manufacturing performs and by the subsequent warm extrusion at 743 K. During the compression test at the room temperature, the composite containing a large fraction of crystalline copper displayed a larger plastic strain after yielding. FEM simulation revealed change in fracture modes in the composites depending on the amount of crystalline copper in the composites.

  • PDF

Effect of the Compositional Modulation on the Plasticity of Amorphous Alloys: Shear Localization Viewpoint Interpretation (비정질 합금의 조성분리가 소성에 미치는 영향: 변형국부화 관점에서의 해석)

  • Lee, Mi-Rim;Park, Kyoung-Won;Sa, Hyun-Je;Lee, Jae-Chul
    • Korean Journal of Metals and Materials
    • /
    • v.47 no.11
    • /
    • pp.687-693
    • /
    • 2009
  • Experiments have demonstrated that a moderate amount of Be added to $Zr_{57.5}Cu_{38.3}Al_{4.2}$ amorphous alloy enhances the plasticity of the alloy. In particular, $Zr_{54}Cu_{36}Al_{4}Be_{6}$ alloy exhibited 19% of strain to fracture along with a strength exceeding 2 GPa. Energy dispersive x-ray spectroscopy conducted on the $Zr_{54}Cu_{36}Al_{4}Be_{6}$ alloy exhibited the presence of compositional modulation, indicating that nm-scale phase separation had occurred at local regions. In this study, the role played by the nm-scale phase separation on the plasticity was investigated in terms of structural disordering, structural softening and shear localization in order to better understand the structural origin of the enhanced plasticity shown by the developed alloy.

Crystallization Behavior and Electrochemical Properties of Si50Al30Fe20 Amorphous Alloys as Anode for Lithium Secondary Batteries Prepared by Rapidly Solidification Process (액체급랭응고법으로 제조된 리튬 이차전지 음극활물질용 Si50Al30Fe20 비정질 합금의 결정화 거동 및 전기화학적 특성)

  • Seo, Deok-Ho;Kim, Hyang-Yeon;Kim, Sung-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.32 no.4
    • /
    • pp.341-348
    • /
    • 2019
  • This paper reports the microstructure and electrochemical properties of Si-Al-Fe ternary amorphous alloys prepared by rapid solidification as an anode for lithium secondary batteries. The microstructure was analyzed using XRD and HR-TEM with EDS mapping. In accordance with DSC analysis, annealing was performed to crystallize the active nano-Si in the amorphous alloy. Thus, nano-Si forms (~80 nm) embedded in the matrix alloy, such as $Fe_2Al_3Si_3$, $FeSi_2$, and $Fe_{0.42}Si_{2.67}$, were successfully synthesized. The electrode based on the Si-Al-Fe ternary alloy delivered an initial discharge capacity of approximately $700mAh^{g-1}$, and exhibited a high Coulombic efficiency of 99.0~99.6% from the $2^{nd}$ to $70^{th}$ cycles.

The Effect of Pr Additive on Magnetostriction of Amorphous Fe-B Alloy (Pr 첨가가 Fe-B 비정질합금의 자왜에 미치는 영향)

  • 조용수;김윤배;김창석;김택기
    • Journal of the Korean Magnetics Society
    • /
    • v.4 no.2
    • /
    • pp.126-129
    • /
    • 1994
  • In order to invetigate the effect of Pr additive on the magnetostriction of amorphous Fe-B alloys, amorphous $Fe_{86-x}B_{14}Pr_{x}(2{\leq}x{\leq}8\;at.%)$ alloys were prepared by a rapid solidification process. As the Pr content increased in the as-prepared amorphous $Fe_{84}B_{14}Pr_{2}$ alloy annealed at $300^{\circ}C$ for 2 hr increased to 70 ppm. Ac power loss and permeability$(f=50\;kHz,\;B_{m}=0.1\;T)$ of the annealed amorphous $Fe_{84}B_{14}Pr_{2}$ alloy were 15 W/kg and $5.5{\times}10^{3}$, respectively.

  • PDF

Hydrogen Permeation Properties of $(Ni_{60}-Nb_{40})_{95}-Pd_5$ Amorphous Metallic Membrane ($(Ni_{60}-Nb_{40})_{95}-Pd_5$ 비정질 금속막의 수소투과 특성)

  • Lee, Dock-Young;Kim, Yoon-Bae
    • Journal of Hydrogen and New Energy
    • /
    • v.19 no.4
    • /
    • pp.359-366
    • /
    • 2008
  • Hydrogen as a high-quality and clean energy carrier has attracted renewed and ever-increasing attention around the world in recent years, mainly due to developments in fuel cells and environmental pressures including climate change issues. In this processes for hydrogen production from fossil fuels, separation and purification is a critical technology. $(Ni_{60}-Nb_{40})_{95}-Pd_5$ alloy ingots were prepared by arc-melting the mixture of pure metals in an Ar atmosphere. Melt-spun ribbons were produced by the single-roller melt-spinning technique in an Ar atmosphere. Amorphous structure and thermal behavior were characterized by XRD and DSC. The permeability of the $(Ni_{60}-Nb_{40})_{95}-Pd_5$ amorphous alloy membrane was characterized by hydrogen permeation experiments in the temperature range 623 to 773 K and pressure of 2 bars. The maximum hydrogen permeability was $3.54{\times}10^{-9}[mol{\cdot}m^{-1}s^{-1}{\cdot}pa^{-1/2}]$ at 773 K for the $(Ni_{60}-Nb_{40})_{95}-Pd_5$ amorphous alloy.

Deposition Behavior and Microstructure of Fe-based Amorphous Alloy Fabricated by Vacuum Kinetic Spraying Process (진공 저온 분사 공정을 통해 형성된 Fe계 비정질 재료의 적층거동 및 미세구조 변화 관찰)

  • Kwon, Juhyuk;Park, Hyungkwon;Lee, Illjoo;Lee, Changhee
    • Korean Journal of Materials Research
    • /
    • v.24 no.1
    • /
    • pp.60-65
    • /
    • 2014
  • Fe-based amorphous coatings were fabricated on a soda-lime glass substrate by the vacuum kinetic spray method. The effect of the gas flow rate, which determines particle velocity, on the deposition behavior of the particle and microstructure of the resultant films was investigated. The as-fabricated microstructure of the film was studied by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Although the activation energy for transformation from the amorphous phase to crystalline phase was lowered by severe plastic deformation and particle fracturing under a high strain rate, the crystalline phases could not be found in the coating layer. Incompletely fractured and small fragments 100~300 nm in size, which are smaller than initial feedstock material, were found on the coating surface and inside of the coating. Also, some pores and voids occurred between particle-particle interfaces. In the case of brittle Fe-based amorphous alloy, particles fail in fragmentation fracture mode through initiation and propagation of the numerous small cracks rather than shear fracture mode under compressive stress. It could be deduced that amorphous alloy underwent particle fracturing in a vacuum kinetic spray process. Also, it is considered that surface energy caused by the formation of new surfaces and friction energy contributed to the bonding of fragments.

A Study on Spring Back in Sheet Forming of Amorphous Alloys (아몰퍼스 판재 성형의 스프링 백에 관한 연구)

  • Yoon S.H.;Lee Y.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2005.06a
    • /
    • pp.1757-1760
    • /
    • 2005
  • This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die corner radius, friction, blank holder force, clearance and initial forming temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling and two modes of spring backs are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.

  • PDF

Spring Back in Amorphous Sheet Forming at High Temperature (아몰퍼스 고온 판재성형시 스프링백)

  • Lee Y-S
    • Transactions of Materials Processing
    • /
    • v.14 no.9 s.81
    • /
    • pp.751-755
    • /
    • 2005
  • This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die comer radius, friction, blank holder force, clearance and initial funning temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling, and two modes of spring back are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.

Novel Properties of Boron Added Amorphous Rare Earth-transition Metal Alloys for Giant Magnetostrictive and Magneto-optical Recording Materials

  • Jai-Young Kim
    • Journal of Magnetics
    • /
    • v.3 no.3
    • /
    • pp.78-81
    • /
    • 1998
  • Large magneto crystalline anisotropy energy and demagnetization energy of rare earth-transition metal (RF-TM) alloys play roles of bottlenecks towards their commercial applications for giant magnetostrictive and blue wavelength magneto optical recording materials, respectively. To solve the above problems, boron is added into amorphous RE-TM alloys to produce its electron transferring. The boron added amorphous RE-TM alloys show novel magnetic and magneto-optical properties as follows; 1) an amorphous $(Sm_{33}Fe_{76})$97B3 alloy obtains the magnetostriction of$ -550{times}10^{-6}$ at 400 Oe compared with saturation magnetostriction of$ -60{\times}10^{-6}$ in conventional Ni based alloys, 2) an amorphous$ (Nd_{33}Fe_{67})_{95}B_5$ alloy increases effective magnetic anisotropy to$ -0.5{\times}10^{-6} ergs/cm^3 from -3.5{\times}10^6 ergs/cm^3$ without boron, which correspond to the polar Kerr rotation angles of 0.52$^{\circ}$and 0.33$^{\circ}$, respectively. These results attribute to selective 2p-3d electron orbits exchange coupling (SEC).

  • PDF