Assignment #3: Imperfections and Diffusion
1. Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 327 C.
Assume an energy for vacancy formation of 0.55 eV/atom.
2. Calculate the activation energy for vacancy formation in aluminum, given that the equilibrium
number of vacancies at 500 C is 7.57x10 23m . The atomic weight and density (at 500 oC) for
aluminum are, respectively 26.98 g/mol and 2.62 g/cm .
3. What is the composition, in atom percent, of an alloy that cons ists of 30 wt% Zn and 70 wt%
4. For an ASTM grain size of 8, approximately how many grains would there be per square inch
(a) at a magnification of 100x, and (b) without any magnification?