MATL913/MATE413 SEM report 1 Characterisation of fracture surface of plain carbon steel samples Charpy impact tested at room temperature and -80°C 1. Materials and mechanical properties Fracture...

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Answered Same DayMay 26, 2021MATL913

Answer To: MATL913/MATE413 SEM report 1 Characterisation of fracture surface of plain carbon steel samples...

Rahul answered on Jun 03 2021
156 Votes
REPORT ON X – RAY DIFFRACTION
Overview of X-Ray Diffraction
1. X-ray diffraction (XRD) mainly depends on the dual nature (particle/wave nature) of
X-rays to get idea about the structure of crystalline materials. This technique
basically used for the identification of compounds based on their diffraction pattern.
When Monochromatic incident beam interacts with target material and through the
slits it scatters of those x-rays from atoms of the target material.
There are two
interference during the X-Ray diffraction which is constructive and destructive
interference. This process by crystals is defined by Bragg’s law, n(lambda) =
2dsin(theta). The direction of diffraction depends on the size and shape of the unit
cell of the material. The intensities of the waves proportional to the kind and
arrangement of atoms. Most of the materials are composed of many tiny crystallites in
all possible orientations called a polycrystalline or powder. When a polycrystalline
with randomly oriented crystallites is placed in way of X-ray beam, the beam will see
all possible interatomic planes. If the experimental angle is systematically changed
then all diffraction peaks from the powder will be detected. It has higher absorption.
There is lower amount needed during the experiment. Neighbours and isotopes
cannot be discriminated. There is hard to detect Light elements
Figure 1: X-Ray Diffraction
Application
a. It is used in sample texture evaluation, thin film analysis, investigation of
sample stress and strain monitoring of crystalline phase and structure
b. It is also used in characterization of crystalline materials, determination of unit
cell dimensions, determine of modal amounts of minerals (quantitative
analysis)
c. There are also some other applications like determine crystal structures using
Rietveld refinement
Advantages
a. In this technique minimal sample preparation is required
b. X-Ray based units are widely available
c. Powerful and rapid technique
d. Data interpretation is very easy
2 Synchrotron Radiation
The synchrotron radiation is an accelerator in which electron are injected and accelerated
to very high form of energy. In this generally electrons are injected at intervals of 20 ms
and accelerated at 5 GeV.
Diffraction with Monochromatic Radiation
Monochromatic radiation’s conventional source is basically long conventional practice.
A specific wavelength is selected from the radiation by using monochromator. So first of
all we fixed the wavelength and try to satisfy the brag condition by adjusting the
orientation of the crystal.
n.lemda = 2d sin(theta)
By using synchrotron radiation double crystal arrangement is used
Advantage of Synchrotron Radiation
a It is very intense and compromises a continuous spectrum
b It is polarised to higher degree and it is pulsed and modulated
c It is highly collimated
d high energy beams to penetrate deeper into matter
e Using radiation with small length helps to study the tiny feature of the target material
f The main advantage of this radiation is it can be coherent and polarised
g It can be flash at higher frequency giving the light at time structure
3 Neutron Diffraction
Neutron diffraction is a non-routine complementary technique allowing detection of light
elements, recording of higher intensity Bragg reflections at high angle, discrimination of
neighbouring elements. Neutron diffraction is new concept in the diffraction. In this
theory of scattering is worked same as x-ray diffraction. According to the wave-particle
dualism neutron are comes under the wave properties. As X-rays neutrons have a
wavelength on the order of the atomic scale (Å) and a similar interaction strength with
matter. Interference pattern generated by neutron can be use in Bragg diffraction
experiment.
There are two method from where neutron can be released from the atom. First one is
fission reactor and second one is spallation source. In fission reactor, nuclei breaks into
lighter particle and liberate 2-3 neutron. In spallation source, proton bombardment of
lead nuclei releasing spallation neutron.
Properties of Neutron
a It has high energy for practical use
b Scattering Power is independent of theta
c Mainly neutron interact with nucleus
d It has lower absorption properties
e During the experiment, large amount of sample is needed
f It is not widely available like x- ray
g Light element can be seen
h Neighbours and isotopes
Application of Neutron Diffraction
a. It is used in synthesis of catalyst
b. It is used in metallurgy process
Part B
i Sample preparation is most important part to get...
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