introduction to advanced material science and …...2009/05/15 · 1 introduction to advanced...
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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
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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
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Processing Structure
Properties Performance
Discipline of Materials Science and Engineering
Three Major Materials
MetalsCeramics Polymers
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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
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Strength of Three Major Materials
Electrical Conductivity of Three Major Materials
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Ancient Chinese Bronze
(商晩期) (商晩期)
Forecast of the importance of major materialsM.F.Ashby (Univ. Cambridge: 1986)
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Forecast of the importance of major materialsDenied by H.Bhadeshia (Univ. Cambridge: 2007)
Still we need advanced metallic materials in society
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What is metal ?
Metals in Periodic Table
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Atom (He)
Electron
Neutron
QuarkProton
Atomic Bonding
Ionic bonding Covalent bonding Metallic bonding
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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
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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.
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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)
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Line Defects (1-Dimensional): Dislocation
Interfacial Defect (2-Dimensional): Grain Boundary
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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.
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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
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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)
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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
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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))
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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.)
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Tremendous Strength of Nanostructured MetalsAluminum with strength as high as steel
(Tsuji: J. Nanoscience & Nanotechnology, 7 (2007), 3763-3770.
Related Articles
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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
??
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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
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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.