1.(a) Draw a schematic 3-D diagram of the unit cells of (i) molybdenum, and (ii) nickel at room temperature. On one of these diagrams, label a specific example of a plane from each of these families of planes: {100}, {111} and {221}. [Please draw your diagrams by hand and scan them.] (b) Describe a technique which can be used to determine crystal structure and the lattice parameter of a finely powdered sample of the phase and compound Cu9Al4. 
2. Pure iron undergoes an allotropic transformation at 910°C: Low-temperature bcc  iron  High-temperature fcc  iron 
(a) Will iron increase or decrease its volume on heating through this temperature? (b) Using crystal geometry, calculate the percentage volume change on heating as the low-temperature cubic I (or bcc) crystal structure transforms to the high-temperature cubic F (or fcc) crystal structure. (c) Under what circumstances might this phenomenon be relevant to an engineer? Why? 
 Page 1 of 2 3. Define and describe the following microstructural features: (a) a grain, (b) a grain boundary, (c) a twin, (d) a precipitate. Why would appropriate chemical etching of a polished section make these various features visible by reflected light microscopy? 
4. (a) By making reference to the concepts of ‘interaction volume’ and ‘escape depth’, Explain why secondary electron imaging, back scattered electron imaging and X-ray mapping, carried out with a scanning electron microscope (SEM), have different spatial resolutions. (b) Why would the spatial resolution of X-ray mapping using a 20 kV beam of electrons differ for (i) aluminium, (ii) copper and (iii) iridium respectively? 
5. (a) With reference to an appropriate spectra, explain how energy dispersive spectroscopy (EDS) enables the composition of a material to be determined. (b) With reference to an appropriate spectra, explain how X-ray photoelectron spectroscopy (XPS) enables the composition of a material to be determined. (c) Which of these two techniques would be best suited to characterising a 7 nm thick oxide on a titanium? Justify your answer.