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MAE 20 Homework_1_summer_2010

# MAE 20 Homework_1_summer_2010 - (h Indicate all the...

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MAE 20 June 30, 2010 Homework 1 Due on Wednesday (July 7), at the beginning of class Clearly show the detailed steps in your solutions. (a) Even though the bonding energies for a ceramic, say MgO, ~ 1000 kJ/mole is larger than that of diamond (~ 700 kJ/mole) why are ceramics more brittle? (b) Give two examples where secondary bonding (van der Waals bonding) is observed? (c) What is the bonding type in diamond? Discuss a property that is commensurate with its bonding? (d) What type(s) of bonding would be expected for: (i) brass, (ii) rubber, (iii) GaAs, (iv) solid xenon, (v) bronze, (vi) Nylon. (e) Would you expect MgO or Mg to have higher strength? Why? (f) Sketch the following directions in a cubic unit cell: (i) [101] (ii) [0 , (iii) [ 2 , (iv) [301] (g) Determine the Miller indices for the four planes shown in the following unit cells:
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Unformatted text preview: (h) Indicate all the directions of the form &amp;lt;110&amp;gt; that lie in the ( 1 plane, of a cubic unit cell. (i) What is the atomic packing fraction? Show that the atomic packing fraction for a body-centered cubic (bcc) crystal is 0.68 (or 68%) (j) Fe has a bcc crystal structure, with an atomic radius of 0.124 nm and an atomic weight of 55.85 g/mole. Compute the value of its theoretical density. (k) Determine the planar density and packing fraction for Nickel (Ni) in the (100), (110), and (111) planes. On which plane is deformation most likely to happen? Why? (l) Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 600 K. Assume an energy for vacancy formation of 0.55 eV/atom....
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