• 제목/요약/키워드: Bulk metallic glasses

검색결과 31건 처리시간 0.028초

벌크비정질합금의 미세성형 : 구성모델과 적용 (Microforming of Bulk Metallic Glasses : Constitutive Modelling and Applications)

  • 윤승채;백경호;김형섭
    • 소성∙가공
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    • 제13권2호
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    • pp.168-173
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    • 2004
  • Microforming can be a good application for bulk metallic glasses. It is important to simulate the deformation behaviour of the bulk metallic glasses in a supercooled liquid region for manufacturing micromachine parts. For these purposes, a correct constitutive model which can reproduce viscosity results is essential for good predicting capability. In this paper, we studied deformation behaviour of the bulk metallic glasses using the finite element method in conjunction with the fictive stress constitutive model which can describe non-Newtonian as well as Newtonian behaviour. A combination of kinetic equation which describes the mechanical response of the bulk metallic glasses at a given temperature and evolution equations fur internal variables provide the constitutive equation of the fictive stress model. The internal variables are associated with fictive stress and relation time. The model has a modular structure and can be adjusted to describe a particular type of microforming process. Implementation of the model into the MARC software has shown its versatility and good predictive capability.

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

  • 신형섭;장순남
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.42-47
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    • 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.

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원자변형률을 이용한 비정질 금속의 천이온도에 관한 연구 (Study for Local Glass Transition of Bulk Metallic Glasses using Atomic Strain)

  • 박준영
    • 한국기계가공학회지
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    • 제10권5호
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    • pp.104-109
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    • 2011
  • Bulk metallic glasses (BMG) have been greatly improved by the advance of synthesis process during last three decades. It was also found that the Glass Forming Ability (GFA) strongly depends on the glass transition temperature. When the temperature approaches to a critical value, the crystals nucleation from the supercooled liquid can be suppressed so that bulk glass formation possible. Egami and others found that the local glass transition temperature depends on the volumetric strain of each atom and suggested the critical transition temperature. In this paper, we explore the strain dependency of local glass transition temperature using the atomic strain defined by the deformation tensor for the Voronoi polyhedra.

$Zr_{55}Cu_{30}Al_{10}Ni_{5}$ 벌크 유리상 금속 변형거동의 변형률속도 의존성 (Strain Rate Dependency of Deformation Behavior in $Zr_{55}Cu_{30}Al_{10}Ni_{5}$ Bulk Metallic Glass)

  • 신형섭;정영진;고동균;오상엽
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1145-1150
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    • 2003
  • Zr-based bulk metallic glasses have a significant mechanical properties such as high strength and elastic strain limit, and a good processing ability due to the deformation behavior such as superplasticity under supercooled liquid region. Recently, many researches on the determination of optimum working condition in various bulk metallic glasses have been carried out. In this study, the deformation behavior and forming conditions of $Zr_{55}Cu_{30}Al_{10}Ni_{5}$ bulk metallic glass were investigated under three different strain rates and at various temperatures between 627K and 727K. The glass transition temperature, crystallization temperature and supercooled liquid region of $Zr_{55}Cu_{30}Al_{10}Ni_{5}$ bulk metallic glass are 680K, 762K and 82K, respectively.

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인체에 유해하지 않은 원소를 사용한 Ti 계 벌크 비정질 합금 개발 (Development of Ti-based Bulk Metallic Glasses with Non-toxic Elements)

  • 이철규;이승훈
    • 한국주조공학회지
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    • 제32권4호
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    • pp.177-180
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    • 2012
  • Ti-based bulk metallic glasses with high glass forming ability were developed through a systematic alloy design technique. The main alloy design strategy was the selection of alloying elements that may not be toxic in the human body. The $Ti_{45.0}Cu_{40.1}Zr_{12.7}Si_{2.2}$ alloy could be cast into an amorphous rod with the diameter of 3 mm by a suction casting technique using Cu mold. The compressive strength of the amorphous rod was measured as 1826 MPa. Since the Ti-based amorphous alloys consist of non-toxic elements, they can be widely used as bio-materials and eco-materials with unique and beneficial properties.

Zr-기 벌크 금속 유리의 마찰 접합 공정 개발 (Development of Friction Welding Process of Zr-based Bulk Metallic Glasses)

  • 신형섭;정영진;김기현
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.337-341
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    • 2004
  • Bulk metallic glasses(BMG) with good mechanical properties have problems that engineering application fields have been limited because of limitation of the alloy size. In order to solving this problem, the friction welding of BMG has been tried using the superplastic-like deformation behavior under the supercooled liquid region. The apparatus for friction welding test was designed and constructed using pneumatic cylinder and gripper based on a conventional lathe. Friction welding have been tried to combination of same BMG alloy and crystalline alloys. The results of welding test were evaluated by X-ray diffraction, measurement of hardness and mechanical properties test. In order to obtain the optimized welding test conditions the temperature of friction interface was measured using Infrared thermal imager.

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Zr계 벌크 비정질 합금의 미세성형 및 평가기술 개발 (Development of nano/micro forming and evaluation technology of Zr-base bulk metallic glass)

  • 옥명렬;서진유;정성재;홍경태;지영수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 추계학술대회논문집
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    • pp.44-47
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    • 2004
  • Although bulk metallic glasses have many outstanding aspects in their chemical, mechanical or functional properties, some critical problems still hinder their wide application. The most important one is the brittle nature of them, which is the serious problem to structural application. So, to use viscous flow is now the only competent way to form bulk metallic glass. In this study, we investigated the basic nature of viscous flow of Zr-base bulk metallic glass, vitrelloy 1, in terms of process variables. The results were used to design the thermo-mechanical process composed of heating, holding, pressing, and cooling, which have unique influence on the glass transition and crystallization behavior. We adopted small load scale and dies with nano/micro patterns on them. The results were evaluated using several analytical methods.

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방전 플라즈마 소결법을 이용한 Al-Ni-Co-Y 벌크 비정질 합금의 제조 (Synthesis of Al-Ni-Co-Y Bulk Metallic Glass fabricated by Spark Plasma Sintering)

  • 이정표;이진규
    • 한국분말재료학회지
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    • 제30권1호
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    • pp.41-46
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    • 2023
  • In this study, an Al82Ni7Co3Y8 (at%) bulk metallic glass is fabricated using gas-atomized Al82Ni7Co3Y8 metallic glass powder and subsequent spark plasma sintering (SPS). The effect of powder size on the consolidation of bulk metallic glass is considered by dividing it into 5 ㎛ or less and 20-45 ㎛. The sintered Al82Ni7Co3Y8 bulk metallic glasses exhibit crystallization behavior and crystallization enthalpy similar to those of the Al82Ni7Co3Y8 powder with 5 ㎛ or less and it is confirmed that no crystallization occurred during the sintering process. From these results, we conclude that the Z-position-controlled spark plasma sintering process, using superplastic deformation by viscous flow in the supercooled liquid-phase region of amorphous powder, is an effective process for manufacturing bulk metallic glass.