• Title/Summary/Keyword: Bulk Amorphous Metal

Search Result 26, Processing Time 0.027 seconds

Deformation Behavior of Zr-based Bulk Metallic Glass by Indentation under Different Loading Rate Conditions (다른 하중속도 조건에서 압입에 의한 벌크 금속유리의 변형거동)

  • Shin, Hyung-Seop;Chang, Soon-Nam
    • Proceedings of the KSME Conference
    • /
    • 2004.04a
    • /
    • pp.42-47
    • /
    • 2004
  • Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications including impact. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation on a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact loading. These results were compared with those of spherical indentation under quasi-static and impact loading. The interface bonded specimens were adopted to observe the appearances of subsurface damage induced during indentation under different loading conditions.

  • PDF

Interfacial Properties of a-Se Thick Films to Solve Charge Trap and Injection Problems (전하 트랩 및 주입 문제를 해결하기 위한 비정질 셀레늄 필름의 계면 특성)

  • 조진욱;최장용;박창희;김재형;이형원;남상희;서대식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2001.11a
    • /
    • pp.497-500
    • /
    • 2001
  • Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). The charge transport properties of amorphous Selenium is decided on hole which is induced from metal to selenium in metal-selenium junction and which is transferred in a-Se bulk. This phenomenon is resulted of changing electric field owing to increasing of space charge by deep trap of a-Se bulk. In this paper, We dopped the chlorine to compensate deep hole trap and deposited blocking layer using dielectric material to prevent from increasing space charge for injection charge between metal electrode and a-Se layer. We compared space charge and the decreasing of trap density through measuring dark and photo current.

  • PDF

Resistive Switching Characteristics of Amorphous GeSe ReRAM without Metalic Filaments Conduction

  • Nam, Gi-Hyeon
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2014.02a
    • /
    • pp.368.1-368.1
    • /
    • 2014
  • We proposed amorphous GeSe-based ReRAM device of metal-insulator-metal (M-I-M) structure. The operation characteristics of memory device occured unipolar switching characteristics. By introducing the concepts of valance-alternation-pairs (VAPs) and chalcogen vacancies, the unipolar resistive switching operation had been explained. In addition, the current transport behavior were analyzed with space charge effect of VAPs, Schottky emission in metal/GeSe interface and P-F emission by GeSe bulk trap in mind. The GeSe ReRAM device of M-I-M structure indicated the stable memory switching characteristics. Furthermore, excellent stability, endurance and retention characteristics were also verified.

  • PDF

Instrumented Impact Test using Subsize Charpy Specimen for Evaluating Impact Fracture Behavior in Bulk Amorphous Metals (벌크 아몰퍼스 금속의 충격파괴 거동 평가를 위한 미소 샬피 시험편을 사용한 계장화 충격 시험법)

  • Shin, Hyung-Seop;Ko, Dong-Kyun;Jung, Young-Jin;Oh, Sang-Yeob;Kim, Moon-Saeng
    • Proceedings of the KSME Conference
    • /
    • 2003.04a
    • /
    • pp.101-106
    • /
    • 2003
  • In order to investigate the mechanical behavior of newly developed materials, the evaluation of mechanical properties using small-size specimen is essential. For those purposes, an instrumented impact testing apparatus, which provides the load-displacement curve under impact loading without oscillations, was devised. To develop the test procedure with the setup, the impact behaviors of various kinds of structural materials such as S45C, SCM4, Ti alloys (Ti-6V-4Al) and Zr-based bulk amorphous metal, were investigated through the instrumented Charpy V-notch impact tests. The calibrations of the dynamic load and displacement that was calculated based on the Newton' second law were carried out through the quasi-static load test and the comparison of a directly measured value using a laser displacement meter. Satisfactory results could be obtained. The crack initiation and propagation processes during impact fracture could be well divided on the curve, depending on the intrinsic characteristic of specimen tested; ductile or brittle. The absorbed impact energy in Zr-basd BAM was largely used for crack initiation not for crack propagation process. The fracture surfaces under impact loading showed different feature when compared with the static cases.

  • PDF

Interfacial Properties of a-Se Thick Films to Solve Charge Trap and Injection Problems (전하 트랩 및 주입 문제를 해결하기 위한 비정질 셀레늄 필름의 계면 특성)

  • Cho, J.W.;Choi, J.Y.;Park, C.H.;Kim, J.H.;Lee, H.W.;Nam, S.H.;Seo, D.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2001.11b
    • /
    • pp.497-500
    • /
    • 2001
  • Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e.g. As, Cl). The charge transport properties of amorphous Selenium is decided on hole which is induced from metal to selenium in metal-selenium junction and which is transferred in a-Se bulk. This phenomenon is resulted of changing electric field owing to increasing of space charge by deep trap of a-Se bulk. In this paper, We dopped the chlorine to compensate deep hole trap and deposited blocking layer using dielectric material to prevent from increasing space charge for injection charge between metal electrode and a-Se layer. We compared space charge and the decreasing of trap density through measuring dark and photo current. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹

  • PDF

Deformation and Fracture Behavior of Structural Bulk Amorphous Metal under Quasi-Static Compressive Loading (준정적 압축하에서 구조용 벌크 아몰퍼스 금속의 변형 및 파괴거동)

  • Shin, Hyung-Seop;Ko, Dong-Kyun;Oh, Sang-Yeob
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.27 no.10
    • /
    • pp.1630-1635
    • /
    • 2003
  • The deformation and fracture behaviors of a bulk amorphous metal, Zr-based one (Zr$\_$41.2/Ti$\_$13.8/Cu$\_$12.5/Ni$\_$10/Be$\_$22.5/: Vitreloy), were investigated over a strain rate range (7x10$\^$-4/~4 s$\^$-1/). The uniaxial compression test and the indentation test using 3mm-diameter WC balls were carried out under quasi-static loading conditions. As a result, at the uniaxial compressive state, the fracture stress of the material was very high (~1,700MPa) and the elastic strain limit was about 2%. The fracture strength showed a strain rate independent behavior up to 4 s$\^$-1/. Using indentation tests, the plastic deformation behavior of the Zr-based BAM up to a large strain value of 15% could be achieved, even though it was the deformation under locally constrained condition. The Meyer hardness of the Zr-based BAM measured by static indentation tests was about 5 GPa and it revealed negligible strain hardening behavior. At indented sites, the plastic indentation occurred forming a crater and well-developed multiple shear bands were generated around it along the direction of 45 degree when the indentation load exceeded 7kN. With increasing indentation load, shear bands became dense. The fracture surface of the specimen after uniaxial compressive tests showed vein-like pattern, typical morphology of many BAMs.

Bulk Amophisation and Decomposition Behavior of Mg-Cu-Y Alloys (Mg-Cu-Y합금의 벌크 비정질화 및 상분해 거동)

  • Kim, S.H.;Kim, D.H.;Lee, J.S.;Park, C.G.
    • Applied Microscopy
    • /
    • v.26 no.2
    • /
    • pp.235-241
    • /
    • 1996
  • Amophization and decomposition behaviour in $Mg_{62}Cu_{26}Y_{12}$ alloy prepared by melt spinning method and wedge type metal mold casting method have been investigated by a detailed transmission electron microscopy. Amorphous phase has formed in melt-spun ribbon. In the case of the wedge type specimen, however, the amorphous phase has formed only around the tip area within about 2 mm thickness. The remaining part of the wedge type specimen consists of crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$. The supercooling for crystallization behaviour of the amorphous $Mg_{62}Cu_{26}Y_{12}$ alloy, ${\Delta}T_x$ has been measured to be about 60 K. Such a large undercooling of the crystallization bahaviour enables formation of the amorphous phase in the $Mg_{62}Cu_{26}Y_{12}$ alloy under the cooling rate of $10^{2}K/s$. The amorphous $Mg_{62}Cu_{26}Y_{12}$ has decomposed into crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$ after heat treatment at $170^{\circ}C\;and\;250^{\circ}C$.

  • PDF

Metallizations and Electrical Characterizations of Low Resistivity Electrodes(Al, Ta, Cr) in the Amorphous Silicon Thin Film Transistor (비정질 실리콘 박막 트랜지스터 소자 특성 향상을 위한 저 저항 금속 박막 전극의 형성 및 전기적 저항 특성 평가)

  • Kim, Hyung-Taek
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1993.05a
    • /
    • pp.96-99
    • /
    • 1993
  • Electrical properties of the Thin Film Transistor(TFT) electrode metal films were investigated through the Test Elements Group(TEG) experiment. The main purpose of this investigation was to characterize the electrical resistance properties of patterned metal films with respect to the variations of film thickness and TEG metal line width. Aluminum(Al), Tantalum(Ta) and Chromium(Cr) that are currently used as TFT electrode films were selected as the probed metal films. To date, no work in the electrical characterizations of patterned electrodes of a-Si TFT was accomplished. Bulk resistance$(R_b)$, sheet resistance$(R_s)$, and resistivities($\rho$) of TEG patterned metal lines were obtained. Electrical continuity test of metal film lines was also performed in order to investigate the stability of metallization process. Almost uniform-linear variations of the electrical properties with respect to the metal line displacements was also observed.

  • PDF

Impact Fracture Behaviors of Zr-Based Bulk Amorphous Metals (Zr-기 벌크 아몰퍼스 금속의 충격 파괴 거동)

  • Ko, Dong-Kyun;Jeong, Young-Jin;Shin, Hyung-Seop;Oh, Sang-Yeob
    • Proceedings of the KSME Conference
    • /
    • 2003.11a
    • /
    • pp.1246-1251
    • /
    • 2003
  • The fracture behaviors of Zr-based bulk amorphous metals(BAMs) having compositions of $Zr_{55}Al_{10}Ni_{5}Cu_{30}$, were investigated under impact loading and quasi-static conditions. For experiments, a newly devised instrumented impact testing apparatus and the subsize Charpy specimens were used. The influences of loading rate and the notch shape on the fracture behavior of the Zr-based BAM were examined. The Zr-based BAMs showed an elastic deformation behavior without any plastic deformation on it before fracture. Most fracture energies were absorbed in the process of the crack initiation. The maximum load and fracture absorbed energy under quasi-static condition were larger than those under impact condition. However, there existed relatively insignificant notch shape effect. Fracture surfaces under impact loading were smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the extent of the vein-like pattern region due to the shear bands developed at the notch tip. It can be found that the fracture energy of the Zr-Al-Ni-Cu alloy is closely related with the development of shear bands during fracture.

  • PDF