MEGR 3161 TEST 3 QUESTIONS AND
ANSWERS
Water must be treated as a two-component system since it is composed of two
elements, hydrogen and oxygen. - Correct Answers -False
A single phase system means that there is only one element in the system. - Correct
Answers -False
Graphite is thermodynamically the most stable form of carbon since
a) it has the lowest energy
b) it has the highest melting point
c) it is the softest compared to other forms of carbon such as diamond - Correct
Answers -a
Diamond is a meta-stable phase of carbon since its free energy is higher than that of
graphite, but transformation from diamond to graphite is kinetically forbidden under
ambient condition due to the energetic barrier for this transformation. - Correct Answers
-True
Water will always boil at 100C - Correct Answers -False
Adding a metal of a higher melting point into that of a lower melting point will always
increase the melting point of the latter. - Correct Answers –False
Martensite is formed as long as the temperature is below the Ms (martensite start)
temperature, irrespective of the cooling rate. - Correct Answers -False
All Fe-C alloys have the same Ms (martensite start) temperature. - Correct Answers -
False
The strength and hardness of Fe-C alloys increase with carbon content, while the
ductility decreases with carbon content. - Correct Answers -True
An isomorphous binary system means that adding any amount of one component into
the lattice of another will not change the lattice type. - Correct Answers -True
The copper-nickel phase diagram, as shown by the figure above, has the following
number of phase fields (or regions). - Correct Answers -Three
ANSWERS
Water must be treated as a two-component system since it is composed of two
elements, hydrogen and oxygen. - Correct Answers -False
A single phase system means that there is only one element in the system. - Correct
Answers -False
Graphite is thermodynamically the most stable form of carbon since
a) it has the lowest energy
b) it has the highest melting point
c) it is the softest compared to other forms of carbon such as diamond - Correct
Answers -a
Diamond is a meta-stable phase of carbon since its free energy is higher than that of
graphite, but transformation from diamond to graphite is kinetically forbidden under
ambient condition due to the energetic barrier for this transformation. - Correct Answers
-True
Water will always boil at 100C - Correct Answers -False
Adding a metal of a higher melting point into that of a lower melting point will always
increase the melting point of the latter. - Correct Answers –False
Martensite is formed as long as the temperature is below the Ms (martensite start)
temperature, irrespective of the cooling rate. - Correct Answers -False
All Fe-C alloys have the same Ms (martensite start) temperature. - Correct Answers -
False
The strength and hardness of Fe-C alloys increase with carbon content, while the
ductility decreases with carbon content. - Correct Answers -True
An isomorphous binary system means that adding any amount of one component into
the lattice of another will not change the lattice type. - Correct Answers -True
The copper-nickel phase diagram, as shown by the figure above, has the following
number of phase fields (or regions). - Correct Answers -Three
