introduction to materials characterization.pdf

8/9/2019 Introduction to Materials Characterization.pdf

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Introduction to Materials Characterization

Reading Assignment

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Materials Science & Engineeringe a urg ca a er a ng neer ng

Ceramic Engineering

etc

Involves establishing relationships between:

.

2. Processing of materials

3. Properties of materials

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composition and/or processingMust know/understand structure and

compos on o exp o proper es

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1 m109

8Radiowaves

Electrons Neutrons Photons

WAVELENTH

1 mm

107

106Microwaves

totelescopes

methods)

Macro

105

104Infrared

Microscopes

tronscatterin

EM,

SEM

)

Micro

http://www.

1 m103

102UV

ge(v

ariousne

icationrange(

no

Visiblelight

mms.sav.s

k/data

1 nm

101

100

-rays

hods

pplicationra

Appl

ic

Na /file

s/626.jpg

Figure adapted fromM. De Graef and M.E.

10-1

10-2

ays

X

Diffractionme

nAto

M.J. Mills

15

,Materials, CambridgeUniversity Press,

Cambridge UK (2007)p. 5.

1 pm10-

10-4Gamma

Nuc

lear


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Hierarchy of structure

Objects can be observed with the naked eye.

Mesostructure: .

Objects can be viewed by means of optical microscopy

techniques. Objects are micron sized (~0.001 mm).

Nanostructure:

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Objects have sizes between 1 nm and 100 nm.


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Table 1.2. The scale of microstructural features, the magnification required toreveal the feature, and some common techniques available for studying the

.Scale Macrostructure Mesostructure Microstructure Nanostructure

Typical

Magnification

1 100 - 1000 10,000 1,000,000

Common

experimental

techniques

Visual inspection Light Opticalmicroscopy

Scanning andtransmission

electronmicroscopy

X-ray diffraction

x-ray radiography Scanning electronmicroscopy

Atomic forcemicroscopy

Scanningtunneling

microscopy

Ultrasonic Hi h-resolutioninspection transmission

electronmicroscopy

Characteristic Production defects Grain and particle Dislocation Crystal and

microstructuralfeatures

sizes substructure interface structure

Porosity, cracksand inclusions

Phase morphologyand anisotropy

Grain and phaseboundaries

Point defects andpoint-defect

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clusters

Precipitationphenomena


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What characterizes structure?

Structure characterized b size, sha e, volume fraction, and

Microstructure

arrangement of grains of different phases or of a single phase.

Substructure Structure characterized by the type, arrangement, and density

of line defects or by the size shape and orientation of

su gra ns.

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Describes of the atomic arrangement within phases.


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What do we want to identify?

Distinct crystallographic phases in materials.

Phase mor holo i.e. size sha e s atialdistribution, etc.).

E.g., laths, spheroids, etc

Chemistries of bulk materials and/or individual

phases.

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Can you think of any others?


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Levels of AnalysisQualitative

AnalysisIdentification of:

Phaseidentification

Microstructuralmorphology

Microchemicalidentification

Medium carbon Ferrite and Ferrite consists(2) phase morphology

(size and shape);(3) chemical

constituents making

steels consist of amixture of ferriteand cementite

cementite have alamellarmorphology in med.

primarily of Fe.Cementite consistsof Fe and C in a 3:1

up each phase. .

-Fe

Fe3C

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ww.msm.cam.ac.uk/phase-trans/2005/pearlite.JPG

http://www.spaceflight.esa.int/impress/text/education/Images/Glossary/GlossaryImage%20032.png


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Levels of AnalysisQuantitative

AnalysisDetermination of:

Appliedcrystallography Stereology

Microchemicalanalysis

(Bravais lattices) How are the What is the

(crystallography);(2) spatial relationships

between micro-structural features

Ferrite is BCC;

Cementite isprimitive

phases oriented

relative to eachother?

chemistry of each

phase?

(stereology);(3) micro-chemical

composition

(microanalysis).

http://neon.mems.cmu.edu/degraef/research.html

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001 211 , 100 0 11

101 112 , 010 111


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Levels of AnalysisQuantitative

AnalysisDetermination of:

Appliedcrystallography Stereology

Microchemicalanalysis

(Bravais lattices) How are the What is the

(crystallography);(2) spatial relationships

between micro-structural features

Ferrite is BCC;

Cementite isprimitive

phases oriented

relative to eachother?

chemistry of each

phase?

(stereology);(3) micro-chemical

composition

(microanalysis).

Fig. 4. Atom maps of the selected volume of 4 20 50 nm3 in the- .

yellow dots and the small blue dots represent carbon (100% shown)and iron (50% shown), respectively. The bottom figure shows thecorresponding 1D carbon concentration profiles along the directionperpendicular to the lamellar interfaces (also the probing direction).The error bars are marked in ra . Fi ure from Y.J. Li, P. Choi, C.Borchers, S. Westerkamp, S. Goto, D. Raabe, and R. Kirchheim,ActaMaterialia 59 (2011) 3965-3977.

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Something that will interact with

atoms making up a materialPROBElight, x-rays, electrons, etc

analyzing/characterizing

Specimen-probe interaction

What is generated after the probe

interacts with a material

SIGNAL

23Pattern, spectrum, image, etcIMAGE INTERPRETATION


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Some Common Characterization Methods

Visible light

Optical microscopy (OM)

Electron beams

Scanning electron microscopy

X-rays

X-ray diffraction (XRD) Transmission electron

microscopy (TEM)

-ray p otoe ectronspectroscopy (XPS)

Neutrons

Energy dispersive x-rayspectroscopy (EDS)

Wavelength dispersive x-ray

Neutron diffraction (ND)

Ion beams

spectroscopy (WDS)

Auger electron spectroscopy(AES)

Secondary ion massspectrometry (SIMS)

Focussed ion beam (FIB)

Electron energy lossspectroscopy (EELS)

microscopy

Cleaning and thinning samples2424


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Probe is scattered by a solid.

Material

Incidentphotonsof EM

radiation

Scatteredphotons of EM

radiation

Absorber

We use this scattered si nal to characterize

the structure of a material

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Scattering primary mechanism for reduction of the

intensit of the incident beam.Material

Incidentphotonsof EM

radiation

Scatteredphotons of EM

radiation

Absorber

Elastic scattering little/no change in energy betweenthe incident photon and the emitted photon.

incident photon and the emitted photon.

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General Types of Experimental Techniques

Microscopy

Obtain a 2-D (or 3-D) image of a specimen.

Diffraction

Incident signal is deflected w/o intensity loss.Scattered si nal is dis la ed as a diffraction attern

or spectrum.

Some of incident signal intensity is lost. Collect signal

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.


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1 3

2 4

1. Signal can be focused real space imagee. . OM SEM TEM

3. Energy loss spectradue to absor tion o incident radiation

2. Scattering angles can be collected andanalyzed in reciprocal space

4. Secondary signals such as x-rays orsecondary electrons

(e.g., XRD or SAD) (due to excitation of electrons in material)

(Figure from D.Brandon and W. Kaplan, Microstructural Characterization of Materials, 2nd Edition, Wiley (2008) p. 6)


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Elastic ScatteringImages vs. Diffraction Patterns

Real

Optical System(Lens)

Real space. Distances in magnified

ima e are directlMAGNIFIED

ec

Image

proportional to

distances in object.

Focusedimage

Realobject

= M

29http://www.socialearth.org/wp-content/uploads/2009/12/magnifying-glass.jpg


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Elastic ScatteringImages vs. Diffraction Patterns

IncidentDiffr

Pa

Reciprocal space. Scattering angle is

inversel ro ortional to

Object

ac

tion

tte

rn

separation of featuresin an object!Scattering angle

Scattered Radiation

Angle d-1

110

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Inelastic

ca er ng

Designed to scan surface anddetect loss spectra or secondarysi nals (e. ., secondarelectrons).

We use these signals to get image

resolution images), determinechemistry, etc

Figure 1.5 A scanning image is formed by scanning a focused probe over the surface of aspecimen and collecting a data signal from it. In an SEM, the signal is processed and

displayed on a fluorescent screen with the same time base as that used to scan the probe.

The si nal ma be secondar electrons characteristic X-ra s or a wide variet of other

excitation phenomena. (Figure from D.Brandon and W. Kaplan, MicrostructuralCharacterization of Materials, 2nd Edition, Wiley (2008) p. 6)


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-

-

Elastic constants.

-

Yield strength.

coefficient.

S ecific ravit .

.

Dislocation density.

Vacancy or interstitial

Etccontent.

Conductivity (thermal and

. Fracture toughness.

c

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Common Units of Measure in Materials

Unit Equal to Comments

Traditional unit of measure for EM

Wavelength - m ra a on. overs v s e por on

of EM spectrum and x-rays.1 nm 10 or 10-9 m SI units. Not very popular.

Energy 1 eV1.602 10-19 J

1.602 10-12 ergs

Energy to move a single electronthrough a potential (Voltage)difference.

Unit cell dimensions are defined in termsof Angstroms ()

Approximately 3 eV or more of energy isrequired for self diffusion in solids! b

a

33xy

z


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10-6

Wavelengthin nm

Frequency incycles per second

1020

One angstrom 10-1

Gamma raysViolet

Indigo

nm

450

400

1015 One micrometer

ne nanome er 1

Ultraviolet

X-rays

Visible Light

ue

Green

Yellow600

550

500

1010 One centimeter

n rare

Short radio waves

Red

700

650

5One kilometer

One meter 109

Broadcast band

Short radio waves 750

~1014 Long radio waves

X-rays: ~0.5 2.5 Electrons: ~0.05

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For high-resolution characterization, x-rays and electrons are superior to light.

WHY?


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Electromagnetic Spectrum

400 nm 700 nm

Gamma rays X-rays ultraviolet infrared radio

10-16 10-12 10-8 10-4 100 104

1023 1019 1015 1011 107 103

108 104 100 10-4 10-8 10-12Energy (electron-volts)

Frequency (hertz)

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Figure modeled afterhttp://mrbarlow.files.wordpress.com/2007/09/em_spectrum.jpg


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introduction to materials characterization.pdf

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