Concrete, microstructure, properties and materials - Metha e Monteiro
Microstructure and Propertie s of Engineering Materials
Transcript of Microstructure and Propertie s of Engineering Materials
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Microstructure and Properties of Engineering Materials
Helmut Clemens and Svea Mayer
Department of Physical Metallurgy and Materials Testing
Montanuniversität Leoben, Roseggerstraße 12, 8700 Leoben, Austria
presented by
Peter Staron
Institut für Werkstoffforschung, Helmholtz-Zentrum Geesthacht
Application of Neutron and Synchrotron Radiation in Engineering Materials Science
1 m 1 km 10000 km 1Mio. km10 cm
nanotechnology nano/microstructure component
1 Å 1 nm 100 nm 1 µm 100 µm 1 mm 1 cm 1 m
Dimensions in materials science
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Bonding
Engineering materials
• metallic shining• excellent electrical and thermal conductivity• good deformability
“The (R)Evolution of engineering materials
Intermetallics
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Microstructure of metallic materials
- phase (fcc)
- phase (bcc)
Mutual solubility!
Microstructure & strength of metallic materials
growth of pores
grain boundary sliding
Low temperature (T < 0.3·TM) High temperature (T > 0.3·TM)
dispersion
solid solution
precipitation
deformation
climb (dislocationcreep)
fine grain
recovery & recrystallisation
diffusional creep
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Microstructural parameters
dislocation density:
grain size:
subgrain/domain size:
concentration of alloying elements:
size and volume fraction of particles: (precipitates, dispersoids)
1010 – 1016 m-2
nm – dm range
nm – µm
ppm – 50%
nm – µm range,0 – 70%
phase morphology and arrangement
The following microstructural parameters determine the properties of engineering (metallic) materials:
Arrangement of the specific constituents MICROSTRUCTURE
-ferrite (bcc) + cementite (Fe3C)
martensite (distorted bcc lattice)
Example: plain carbon steel
residual stresses due to martensitic
transformation
Microstructure & strength
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HRTEM
Microstructure & deformation behaviour
Plastic deformation corresponds to the motion of dislocations in response to an applied shear stress!Plastic deformation corresponds to the motion of dislocations in response to an applied shear stress!
A dislocation is a crystalline defect
Microstructure & deformation behaviour
superplasticity
fcc lattice
(Cu, Al, Ni)
hex lattice
(Mg, -Ti)
0211}0001{ 011}111{
slip plane
slip direction
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Texture
x
y
pole figure
x
y
z
no texture isotropic mechanical properties
x
y
x
y
z
strong texture anisotropic mechanical properties
x
y
“cube” texture
Texture
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Textures in engineering materials: pros & cons
Iron Nickel
Steel
Formation of texture
cold – working hot – working annealing
10 µm
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Recovery and recrystallisation
Recrystallisation
Recovery
10 µm
deformed state annealed state
Mechanisms of recovery
Polygonisation and subsequent growth of subgrains
10 µm
subgrains in Al
Interstitial atoms diffuse to vacancies
Annihilation of dislocations showing opposite signs
Condensation of vacancies
Formation of subgrains(polygonisation). Reduction of dislocation energy
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Recrystallisation
Brass(Cu-Zn alloy)
cold-worked (33%)
580°C/3sec
580°C/4sec 580°C/8sec
In-situ deformation experiment
Synchrotron radiation storage ring with bending magnets → high energy X-rays
Sample
Detector (image plate or CCD)
Monochromator
Deformation device
Temperature
Force
Time
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Debye-Scherrer rings of a three-phase TiAl alloy
Ti-43Al-4Nb-1Mo-0.1B (at%)
o
/2
In-situ – investigation using synchrotron radiation
In-situ deformation experiment
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XRD patterns ↔ microstructure
Response of patterns on processing
Response of patterns on processing
deformation & temperature
XRD patterns ↔ microstructure
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Microstructure after thermo-mechanical processing
Precipitation hardened Fe - Co - Mo steel
Fine secondary - phasenot visible
Martensitic matrix
(Fe - Co - Mo)
Coarse secondary - phase
(Fe,Co)7Mo6
Precipitation hardening
3 x 1h
Example: ordinary and and advanced tool steels
3 x 1h
homogeneous solid solution
coherent precipitates
Particle coarsening
“Oswald ripening”
loss of coherency
3P tr
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Information on: ● crystal structure
● chemical composition
● particle size
● interface structure
electron source
condensor lenses
objective lens
specimen
projective lens
eye
light microscope
viewing screen
negative plates or camera
isolator
Transmission Electron Microscopy
Characterization of precipitates
Transmission electron microscopy (TEM)
Example: Advanced steel based on Fe-Co-Mo
Conventional TEM
Coarse secondary - phase
(Fe,Co)7Mo6
High-resolution TEM
Fine secondary - phase
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3D - atom probe (3DAP)
high voltage
Pulsecommand
time of flightmeasurement
impact location
20 to 100 K
3 to 15 kV
X
Y
2
2ges
d
tVe2
n
m
Characterization of nm-sized precipitates
Information on: ● chemical composition
● volume fraction
● particle size
r ~ 50nm
samplefield evaporation
Example: Advanced steel based on Fe-Co-Mo
Intermetallic -(Fe,Co)7Mo6
precipitates
Martensitic matrix
(Fe - Co - Mo)
Three-dimensional atom probe
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Small-angle neutron scattering (SANS)
Information on: ● particle size distribution (1–100 nm)
● volume fraction
large sample volume
no direct information
mag.+ nuc.
nuc.
H
SANS beamline assembly:
Example: Advanced steel based on Fe-Co-Mo
0,1 110-2
10-1
100
101
102
103
540°C615°C675°C
d/d
[cm
–1sr
–1]
q [nm–1]
0 5 10 150,00
0,02
0,04
0,06
0,08
0,10
0,12 540 °C 615 °C 675 °C
f (R
) [n
m–
1]
R [nm]
SANS curves and size distributions
Evolution of the fine -(Fe,Co)7Mo6
precipitates with ageing temperature
(and time)
Small-angle neutron scattering (SANS)
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Tem
pera
ture
[°C
]
1000
1100
1200
1300
1400
1500
1600
36 40 44 48 52 56
Aluminium [Atomic-%]
+
2
2 +
L
Evolution of a fully lamellar microstructure
Example:
Evolution of a fully lamellar microstructure
Phase transformations
→
+
2
2 +
L
Tem
per
atu
re [
°C]
1000
1100
1200
1300
1400
1500
1600
36 40 44 48 52 56
Aluminium [At%]
-Tr
ansu
s Li
ne
Information on: ● phase transformations
● thermal expansion coefficient
● in-situ deformation studies
Volume change due to phase transformation
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In-situ – investigation using synchrotron radiation
Debye-Scherrer-cone
sample
high-energy X-ray beam
detectors
2
0
Time
2 /2Precipitation of -TiAl lamellae
(d) (e)
Phase diagrams & phase fractions
Calculated phase diagram
The corresponding diffraction pattern are analyzed by Rietveld methodThe corresponding diffraction pattern are analyzed by Rietveld method
Information on:
● occurring phases and their volume fractions
● phase transformations
● phase transition temperatures
● kinetics of phase transformations
● order/disorder reactions
● …….
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Ordering behaviour
Structure Powder Diffractometer (SPODI) at FRM II in Munich, Germany λ = 1.55 Å.
sin
4
q
Ti-43.9-Al-3.8Nb-1Mo-0.1B (at%)
Scattering lengths:
bAl ~ -bTi
→ in-situ neutron diffraction
In TiAl-based alloys only reflections of orderedphases are visible!In TiAl-based alloys only reflections of orderedphases are visible!
?
Ordering/disordering behaviour → in-situ neutron diffraction
Heating rate: 10 Kmin-1
Loss of order in the o-phase is indicated by a sharp drop in intensity of the corresponding reflection
Loss of order in the o-phase is indicated by a sharp drop in intensity of the corresponding reflection
To
rd
1225
°C
Two-axes powder diffractometer (WOMBAT) at ANSTO in Menai, Australia.λ = 1.67 Å.
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Summary
Important information needed:● grain/subgrain/domain size
● crystal structure and chemistry
● preferred grain orientation (texture)
● 3-dimensional arrangement of phases
● phase transitions (onset, temperatures...)
● size and volume fraction of particles(precipitates, dispersoids)
● structure and type of appearing interfaces
● types of defects and defect density (pores, cracks…)
● vacancy concentration and dislocation density
● local/residual stresses
● microstructural evolution during deformation and/or thermal treatment
● nucleation and growth processes
● order/disorder reactions….
References and Acknowledgements
References & further reading:
W.D. Callister Jr., Materials Science and Engineering - An Introduction,
John Wiley & Sons
T.H. Courtney, Mechanical Behavior of Materials, McGraw - Hill
M.F. Ashby and D.R.H. Jones, Engineering Materials, Vols. 1 & 2, Pergamon Press
R.E. Smallman and R.J. Bishop, Modern Physical Metallurgy & Materials
Engineering, Butterworth - Heinemann
M.F. Ashby, Materials Selection in Mechanical Design, Pergamon Press
G. Gottstein, Physikalische Grundlagen der Materialkunde, Springer Verlag
W. Reimers, A.R. Pyzalla, A. Schreyer, and H. Clemens (Editors),
Neutron and Synchrotron Radiation in Engineering Materials Science,
WILEY-VCH
Special Issue: Advanced Engineering Materials 13 (2011) 635-850.
Valuable contributions of the following persons are gratefully acknowledged:
Christina Scheu, Peter Staron, Andreas Stark, Andreas Schreyer, Klaus-Dieter Liss, Arno Bartels, Heinz-Günter Brokmeier, Gerhard Dehm, Thomas Schmölzer, Martin Schloffer, Emanuel Schwaighofer, Elisabeth Eidenberger, Michael Schober, .…