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Transcript of Introduction to Advanced Material Science and …...2009/05/15  · 1 Introduction to Advanced...

  • 1

    Introduction to Advanced Material Science and Technology先端マテリアルサイエンス通論

    Nanostructure Control in Structural Metallic Materials

    構造用金属材料におけるナノ組織制御

    Nobuhiro TSUJI (辻 伸泰)Department of Materials Science and Engineering

    材料工学専攻

    May 15, 2009: class

    Outline of the lecture:

    1. Metallic Materials

    2. Imperfections in Crystal Structure andMicrostructures of Materials

    3. Ultrafine Grained or Nanocrystalline Metalsas a New Class of Advanced Material

  • 2

    Outline of the lecture:

    1. Metallic Materials

    2. Imperfections in Crystal Structure andMicrostructures of Materials

    3. Ultrafine Grained or Nanocrystalline Metalsas a New Class of Advanced Material

    Material物質 busshitsu 材料 zairyo

    Materials Science& Engineering

    物質科学 材料工学

  • 3

    Processing Structure

    Properties Performance

    Discipline of Materials Science and Engineering

    Three Major Materials

    MetalsCeramics Polymers

  • 4

    Three Major Materials• Metals

    Metallic Bonding; Strength and Ductility (Deformability);Electric and Thermal Conductivity; Metallic Gloss

    • CeramicsCompounds of Metals and Non-Metals; Cement; Glass;Stability against Heat and Severe Environments

    • PolymersOrganic Compounds; Plastic; Gum; Low Density; Easyto Bend

    Density of Three Major Materials

  • 5

    Strength of Three Major Materials

    Electrical Conductivity of Three Major Materials

  • 6

    Ancient Chinese Bronze

    (商晩期) (商晩期)

    Forecast of the importance of major materialsM.F.Ashby (Univ. Cambridge: 1986)

  • 7

    Forecast of the importance of major materialsDenied by H.Bhadeshia (Univ. Cambridge: 2007)

    Still we need advanced metallic materials in society

  • 8

    What is metal ?

    Metals in Periodic Table

  • 9

    Atom (He)

    Electron

    Neutron

    QuarkProton

    Atomic Bonding

    Ionic bonding Covalent bonding Metallic bonding

  • 10

    Properties Derived from Metallic Bonding

    • High Electrical Conductivity• High Thermal Conductivity• Metallic Gloss• Large Ductility (Deformability)

    Metallic bonding

    Outline of the lecture:

    1. Metallic Materials

    2. Imperfections in Crystal Structure andMicrostructures of Materials

    3. Ultrafine Grained or Nanocrystalline Metalsas a New Class of Advanced Material

  • 11

    Body Centered Cubic (BCC)α-Fe, Mo, W, etc.

    Face Centered Cubic (FCC)γ-Fe, Al, Cu, Ni, etc.

    Hexagonal Close Packed (HCP)Ti, Mg, Zr, etc.

    Crystal Structures of Metals

    Crystal Structures of Metals

    In solid metals, atoms (metallic ions) are periodically alignedin 3-dimensional space, to form crystal lattices.

    However, the crystals are not perfect in general, but involvesvarious kinds of imperfections (lattice defects).

    The lattice defects construct microstructures in metals, whichdetermine the properties of metallic materials.

  • 12

    Point Defects (0-dimensional)Vacancy, Interstitial Atoms,Impurity Atoms

    Line Defects (1-dimensional)Dislocation

    Interfacial Defects (2-dimensional)Grain Boundary, Stacking Fault,Interphase Boundary, Surface

    Volume Defects (3-dimensional)Precipitates, Second Phase,Voids

    (a)(b)(c)

    Various Kinds of Lattice Defects (Imperfections)

    2nd phase grain boundary

    crack void

    twin

    fine precipitates

    dislocation loop

    dislocation network

    dislocations

    dislocation pile-upinclusion on grain boundary

    vacancy

    (edge) dislocation

    substitutional atom(impurity)

    interlattice atom

    (coherent) precipitate

    interstitial atom(impurity)

    Point Defects (0-Dimensional)

  • 13

    Line Defects (1-Dimensional): Dislocation

    Interfacial Defect (2-Dimensional): Grain Boundary

  • 14

    Plastic Deformation by Dislocation Motion (Slip)

    Plastic Deformation by Dislocation Motion (Slip)

    Plastic deformation of crystalline metals is generallyproduced by dislocation slips.Therefore, “easiness” of dislocation motion determines the“strength” of metals.

  • 15

    Point Defects (0-dimensional)Vacancy, Interstitial Atoms,Impurity Atoms

    Line Defects (1-dimensional)Dislocation

    Interfacial Defects (2-dimensional)Grain Boundary, Stacking Fault,Interphase Boundary, Surface

    Volume Defects (3-dimensional)Precipitates, Second Phase,Voids

    (a)(b)(c)

    Various Kinds of Lattice Defects (Imperfections)

    2nd phase grain boundary

    crack void

    twin

    fine precipitates

    dislocation loop

    dislocation network

    dislocations

    dislocation pile-upinclusion on grain boundary

    vacancy

    (edge) dislocation

    substitutional atom(impurity)

    interlattice atom

    (coherent) precipitate

    interstitial atom(impurity)

    Outline of the lecture:

    1. Metallic Materials

    2. Imperfections in Crystal Structure andMicrostructures of Materials

    3. Ultrafine Grained or Nanocrystalline Metalsas a New Class of Advanced Material

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    Grain Boundary

    Polycrystals

    Grain Boundaries as Obstacles for Dislocation Motion

  • 17

    σ = σ0 + k d -1/2

    Grain Boundary Strengthening (Hall-Petch Relationship)

    The minimumgrain size we

    can obtain hasbeen

    approximately10µm.

    ConventionalGrainSize

    Ultrafine Grainsor

    Nanocrystals

    UFG/Nanocrystalline Materials are Full of GB

    It is not surprising if theUFG/Nano materials

    perform various uniqueproperties that have not

    yet been observed incoarse-grained materials.

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    How to obtain ultrafine grained (UFG) microstructures ?

    • Vapor Deposition

    • Electric Deposition (Plating)

    • Rapid Solidification• Crystallization of Amorphous

    • Mechanical Milling of Powders

    It is difficult to fabricate bulky materials by theseprocesses.

    Severe Plastic Deformation (SPD) forFabricating Bulky Nanostructured Metals

    Various Kinds of SPD Processes

    N.Tsuji et al. : Advanced Eng. Mater., 5 (2003), No.5, 338.

    Severe Plastic Deformation(SPD: ε > 4)

    Ultrafine Grained Structures(d < 1 µm)

  • 19

    1mm thickness× 33km length thin sheet

    Equivalent Strain of 12equals to…..

    33m

    What is Severe Plastic Deformation (SPD) ?

    Fig. Schematic illustration showing the principle ofAccumulative Roll Bonding (ARB).

    Accumulative Roll Bonding (ARB) Process

  • 20

    Repeated Folding & Forging in Traditional Japanese Sword Production

    Typically 15 times ➡ 32,768 layers

    For strength & toughness increase, homogenization ofcarbon distribution, removing impurities, and making

    beautiful surface

    Materials successfully ARB-processed in Osaka University:

    Pure-Fe, IF steel, 0.041P-added IF steel, SS400 (Fe-0.13C-0.37Mn), Fe-Cr-Ni, duplex stainless steel, Fe-30̃36Ni, pure-Al, 1100Al, 5052Al, 5083Al,6061Al, 7075Al, 8011Al, Al-Cu, Al-Si, Al-Ag, Al+5vol%SiC, OFHC-Cu, Cu-Co-P, Cu-30Zn, Cu-71.9Ag (eutectic), pure Ni, cp-Ti, Mg alloy

    (“SEVERE PLASTIC DEFORMATION: Towards Bulk Production of Nanostructured Materials”, NOVAScience Publishers, New York (2006))

  • 21

    UFG Microstructure in 2N-Al Fabricated by ARB

    (Ito et al., J. Jpn. Inst. Metals, 64(2000), 429.)

    (Huang et al., Mater. Sci. Eng.,A340 (2003), 265.)

    • They are certainly“grains” from a viewpointof misorientations.

    • At the same time, theyare essentiallydeformationmicrostructures(elongated, and involvingsubstructures).

    ARB + Annealing process can produce bulky sheets having variousgrain sizes.

    100℃

    150℃

    200℃

    225℃

    250℃

    300℃

    Change in Microstructure by Annealing-- 1100-Al ARB processed by 6 cycles and then annealed --

    (Tsuji et al.: Scripta Mater., 47 (2002), 893.)

  • 22

    Tremendous Strength of Nanostructured MetalsAluminum with strength as high as steel

    (Tsuji: J. Nanoscience & Nanotechnology, 7 (2007), 3763-3770.

    Related Articles

  • 23

    Unexpected Similarity between UFG Al and Fe

    Yield-Drop Phenomena !!(Tsuji et al.: Scripta Mater., 47 (2002), 893.)

    1100Al(99%Al,2N)

    Hall-Petch curvefor coarse grains

    Extra Hall-Petch Hardening in UFG-Al

    ??

  • 24

    X.Huang, N.Hansen, N.Tsuji: Science,Vol.312, p.249 (2006)

    Al (99%), ARB processed by 6 cycles at RT.

    1: As ARB processed.2: ARB + Annealed at 150°C. (Hardening by Annealing)

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    2: ARB + Annealed at 150°C. (Hardening by Annealing)3: (2) + 15% cold-rolled. (Softening by Deformation)4: (3) + Annealed at 150°C. (Hardening by Annealing, again)5: (4) + 15% cold-rolled. (Softening by Deformation, again)

    Ultrafine grained steelsperform excellent dynamicdeformation behaviors aswell as high strength, whichincrease the safety incollision.

    HONDA has recentlydecided to use an UFG steelfor “Accord” in 2018.

    Application of UFG Steel for Automobile

  • 26

    Processing Structure

    Properties Performance

    Discipline of Materials Science and Engineering

    Summary

    1. Metallic materials have been and will continuously be important

    materials in our society, and improvement of their properties are

    required more and more.

    2. Metallic materials have crystalline structures. The crystals are not

    usually perfect but involve various kinds of imperfections (latticedefects), which construct microstructures. Properties of metals are

    significantly affected by the microstructures.

    3. Ultrafine grained or nanocrystalline metallic materials have been

    recently realized in bulky dimensions. The nanostructured metals showunknown and surprising properties that have not yet been found in

    conventional metallic materials.