MMME4041 – ADVANCED MATERIALS CHARACTERISATION
Coursework 3
Submission date Wednesday 13
th December, 3pm
Answer All Questions
1. (a) With reference to line defects within a crystal structure, explain briefly
the term Burgers vector. As part of your answer, make use of appropriate
sketches to illustrate the difference between a screw dislocation and an
edge dislocation. [3]
(b) With reference to the Miller Indices system, for a simple cubic system,
sketch diagrams to show the following directions and planes: (a) [012],
(b) [12-1], (c) (021) and (d) (22-1). (Denote the origin xyz = 000 of
each diagram clearly.) [4]
(c) Outline briefly the physical basis of X-ray diffraction with reference to a
face centred cubic crystal lattice, and explain the term Structure Factor.
Then, with reference to the Ewald sphere construction, show how Bragg’s
law can be derived in reciprocal space. [6]
(d) Sketch and describe briefly the basic components and geometric
arrangement of a conventional 4-circle X-ray diffractometer. As part of
your answer, explain the importance of the Bragg-Brentano diffraction
geometry. What information content is available within a 2 X-ray
scan [7]
2. (a) With reference to the conventions for digital imaging, explain the terms:
(i) grey level, (ii) gamma correction and (iii) kernel. [3]
(b) Describe briefly: (i) the contrast formation mechanism for secondary
electron (SE) imaging, and (ii) how SEs are detected. [4]
(c) Why is it preferable to use both SE and backscattered electron (BSE)
imaging when investigating a rough sample [2]
(d) Sketch and briefly describe the basic components of an analytical
transmission electron microscope (TEM). As part of your answ
er, outline
how the microscope vacuum levels are maintained, from gun to column
to viewing chamber. [7]
(e) Outline briefly the principles for preparing a thin ( m) diffusion barrier
coating for observation in cross-section geometry within a conventional
TEM. [4]
2
3. (a) With reference to high energy electron, ion or X-ray probe / material
interactions at the heart of many analytical techniques, explain
briefly the terms: (i) elastic scattering; (ii) ionisation edge; (iii) spectral
resolution; (iv) bremsstrahlung; and (v) straggling. [5]
(b) Outline, briefly, the information content provided by the following surface
analysis techniques. State the advantages and limits of applicability of each
technique:
i) Atomic force microscopy (AFM). [5]
ii) Reflection high energy electron diffraction (RHEED) [5]
iii) X-ray photoelectron spectroscopy (XPS) [5]
4. Short essay <1500 words limit>: Briefly outline how an appropriate
combination of complementary analytical techniques, such as optical,
electron or X-ray, along with associated surface profiling and ion beam
techniques, might be used to address the following technical
investigation:
To profile the microstructure across the heat affected zone of an
AerMet / Super-CMV inertia friction weld.
As part of your answer, outline a suitable methodology for the
investigation, and the issues for sample preparation.
Further, the practical modes of operation of the analytical techniques
selected should be emphasised. As appropriate, comment briefly on the
analytical values provided by each technique. [40]
Completed assessments, either hand-written and scanned, or typed, should be
uploaded to Moodle in pdf format, by Wednesday 13
th December, 3pm.