Subject: Materials Engineering/Chemical Engineering (2018)

i. Iron (below 912C ) and tungsten are both Body-Centred Cubic (BCC) with significantly different atomic radii (i.e. RFe=0.124nm,RT=0.141nm ). However, they have the same atomic packing factor of 0.68. How do you explain this? (1.5 Marks) ii. Calculate the planar atomic density in atoms per square millimetre for crystal plane (100) in Face-Centred Cubic (FCC) gold. The lattice constant of gold is 0.40788nm. Show the plane in the cubic cell