UNIVERSITY OF GHANA
DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING
MTEN 605: Kinetics and phase transformation
(2 CREDITS)
Homework 1
This assignment must be done and submitted in pairs
1. Using schematics only, distinguish between the following:
a. Vacancy and self-interstitial
b. substitutional and interstitial solid solution
c. edge dislocation and screw dislocation
d. grain boundary and twin boundary
2. Calculate the number of atoms per cubic meter in aluminum.
3. The concentration of carbon in an iron–carbon alloy is 0.15 wt%. What is the concentration in
kilograms of carbon per cubic meter of alloy?
4. Gold forms a substitutional solid solution with silver. Compute the number of gold atoms per
cubic centimeter for a silver–gold alloy that contains 10 wt% Au and 90 wt% Ag. The
densities of pure gold and silver are 19.32 and 10.49 g/cm3, respectively.
5. Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid
solution in Fe for concentrations up to approximately 20 wt% V at room temperature.
Determine the concentration in weight percent of V that must be added to iron to yield a unit
cell edge length of 0.290 nm.
6. Calculate the number of vacancies per cubic meter in iron at 855 °C. The energy for vacancy
formation is 1.08 eV/atom. Furthermore, the density and atomic weight for Fe are 7.65 g/cm3
and 55.85 g/mol, respectively.
7. Calculate the activation energy for vacancy formation in aluminum, given that the equilibrium
number of vacancies at 500 oC (773 K) is 7.55 × 1023 m-3. The atomic weight and density (at
500 oC) for aluminum are, respectively, 26.98 g/mol and 2.62 g/cm3.
Submit through Sakai/Google Classroom latest by noon on Thursday February 25, 2021.
Thank you.
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