12. A common metal is known to have a cubic unit cell with an edge length of 0.288 nm. If this metal has a density of 7.20 g/cm3 and an atomic weight of 52.0 g/mole, what is its atomic packing factor? Why? 4 marks 13. Determine the Miller indices for the directions shown below: 4 marks A) B) C) D) 14. Determine the Miller indices of the planes shown below A) B) C) A) B) C) 6 marks 11. Steel initially containing 0.002% N is to be nitrided to obtain a concentration of 0.12% N at a distance of 0.0051 cm below the surface. The surface concentration is maintained at 0.15% and the temperature is 625°C. How long will this treatment take? Diffusing Species N 4 marks Host Metal D0 (m2 /s) Qd (kJ/mol) α-Fe 4.7 x 10-7 76.6

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