MTE FINAL EXAM QUESTIONS AND
ANSWERS ALL CORRECT
The electron band structures of insulators like Al2O3 and intrinsic semiconductors like
Si have band gaps that contribute towards their electrical properties. For these types of
materials, what is the name of the region that lies above the energy band gap? -
Answer- b.
Conduction band
The thermal conductivities of polycrystalline materials are __________ those of single
crystals of the same material. - Answer- less than
Consider the galvanic series (shown below). From the choices provided below, please
select the metals or alloys that may be used to galvanically protect brass. Your possible
choices are: - Answer- b, e, f
cadmium, tin, zinc
Hard magnetic materials display which of the following characteristics? - Answer- a, d
Magnetization and demagnetization may be achieved using relatively high applied fields
& A relatively large hysteresis loop
When light interacts with matter it is said to be attenuated. Attenuation of light (aka how
it interacts) by matter can occur in which of the following ways? - Answer- absorbed,
reflected, scattered, transmitted
Please calculate the magnitude of the magnetic field strength H (in A-turns/m). Please
express your answer numerically - Answer- 200
Please select what determines the characteristic color of a metal. - Answer- c reflected
{The characteristic color is determined by the distribution of wavelengths of the reflected
light radiation that is absorbed.}
Corrosion is said to be a "redox" process. As such, the oxidation portion of a corrosion
reaction is a process that involves - Answer- loss of electrons
Polymers (aka "plastics") may be classified as which of the following based upon how
they are formed - Answer- thermoplastic/ thermosetting
, Consider a particle reinforced composite consisting of a metallic Al matrix that is
reinforced with ceramic SiC particles. As the reinforcement content is increased, how
does the strength of this particle-reinforced composite change? - Answer- increases
Calculate the number of vacancies per cubic meter in metallic Bamalloy at a
temperature of 800°C. The energy for vacancy formation is 1.300 eV/atom, while the
density (D) and atomic weight (AWt) for this metal are 9.25 g/cm3 and 61.85 g/mol,
respectively - Answer- c
7.09e22
Calculate the diffusion flux of carbon through the sheet. The concentrations of carbon at
positions of 2 mm and 20 mm beneath the carburized surface are 1.0 kg/m3 and 0.8
kg/m3, respectively. Assume that the diffusion coefficient for carbon through the sheet is
6.2 ´ 10-11 m2/s at this temperature. The total thickness of the sheet is 25 mm. Some
useful equations and conversion factors are provided below. - Answer- f.
6.89 x 10^-10 kg/(m2 s)
At a temperature of 600 K, the diffusion coefficient for Zn into Cu is 8.32 ´ 10-22 m2/s.
Please determine the activation energy for this process in units of kJ/mol. Some useful
equations are provided below. - Answer- e
190.8
Consider the thin sheet of austenite (i.e., FCC iron). Calculate the diffusivity of carbon,
C, through this sheet in units of m2/s at a temperature of 1125°C. The pre-exponential
constant, D0, is 2.0 ´ 10-5 m2/s and the activation energy for diffusion, Qd, is 142
kJ/mol, respectively - Answer- a.
9.89 x 10^-11 m2/s
A brittle material typically exhibits substantial plastic deformation with high energy
absorption before fracture. Is this true or false? - Answer- false
Consider a single crystal of CMSX-4, a second generation Ni-based superalloy. This
alloy is used in the hottest part of gas turbine engines for aerospace. The matrix phase
has a face-centered-cubic (FCC) crystal structure. This single crystal has been
subjected to a tensile stress that is applied along a [113] crystal direction (aka, the axis).
If slip occurs on a (1 1 1) plane in a [1 0 1] (i.e. [-1 0 1]) direction, please calculate the
stress in MPa at which yielding will occur. The critical resolved shear stress for this alloy
is 800 MPa. - Answer- d.
2155.6
Metals, ceramics, and polymers represent the major classes of materials. Which of
them can be manufactured in crystalline form?
Answers:
a. Metals
b. Polymers
c. Ceramics
ANSWERS ALL CORRECT
The electron band structures of insulators like Al2O3 and intrinsic semiconductors like
Si have band gaps that contribute towards their electrical properties. For these types of
materials, what is the name of the region that lies above the energy band gap? -
Answer- b.
Conduction band
The thermal conductivities of polycrystalline materials are __________ those of single
crystals of the same material. - Answer- less than
Consider the galvanic series (shown below). From the choices provided below, please
select the metals or alloys that may be used to galvanically protect brass. Your possible
choices are: - Answer- b, e, f
cadmium, tin, zinc
Hard magnetic materials display which of the following characteristics? - Answer- a, d
Magnetization and demagnetization may be achieved using relatively high applied fields
& A relatively large hysteresis loop
When light interacts with matter it is said to be attenuated. Attenuation of light (aka how
it interacts) by matter can occur in which of the following ways? - Answer- absorbed,
reflected, scattered, transmitted
Please calculate the magnitude of the magnetic field strength H (in A-turns/m). Please
express your answer numerically - Answer- 200
Please select what determines the characteristic color of a metal. - Answer- c reflected
{The characteristic color is determined by the distribution of wavelengths of the reflected
light radiation that is absorbed.}
Corrosion is said to be a "redox" process. As such, the oxidation portion of a corrosion
reaction is a process that involves - Answer- loss of electrons
Polymers (aka "plastics") may be classified as which of the following based upon how
they are formed - Answer- thermoplastic/ thermosetting
, Consider a particle reinforced composite consisting of a metallic Al matrix that is
reinforced with ceramic SiC particles. As the reinforcement content is increased, how
does the strength of this particle-reinforced composite change? - Answer- increases
Calculate the number of vacancies per cubic meter in metallic Bamalloy at a
temperature of 800°C. The energy for vacancy formation is 1.300 eV/atom, while the
density (D) and atomic weight (AWt) for this metal are 9.25 g/cm3 and 61.85 g/mol,
respectively - Answer- c
7.09e22
Calculate the diffusion flux of carbon through the sheet. The concentrations of carbon at
positions of 2 mm and 20 mm beneath the carburized surface are 1.0 kg/m3 and 0.8
kg/m3, respectively. Assume that the diffusion coefficient for carbon through the sheet is
6.2 ´ 10-11 m2/s at this temperature. The total thickness of the sheet is 25 mm. Some
useful equations and conversion factors are provided below. - Answer- f.
6.89 x 10^-10 kg/(m2 s)
At a temperature of 600 K, the diffusion coefficient for Zn into Cu is 8.32 ´ 10-22 m2/s.
Please determine the activation energy for this process in units of kJ/mol. Some useful
equations are provided below. - Answer- e
190.8
Consider the thin sheet of austenite (i.e., FCC iron). Calculate the diffusivity of carbon,
C, through this sheet in units of m2/s at a temperature of 1125°C. The pre-exponential
constant, D0, is 2.0 ´ 10-5 m2/s and the activation energy for diffusion, Qd, is 142
kJ/mol, respectively - Answer- a.
9.89 x 10^-11 m2/s
A brittle material typically exhibits substantial plastic deformation with high energy
absorption before fracture. Is this true or false? - Answer- false
Consider a single crystal of CMSX-4, a second generation Ni-based superalloy. This
alloy is used in the hottest part of gas turbine engines for aerospace. The matrix phase
has a face-centered-cubic (FCC) crystal structure. This single crystal has been
subjected to a tensile stress that is applied along a [113] crystal direction (aka, the axis).
If slip occurs on a (1 1 1) plane in a [1 0 1] (i.e. [-1 0 1]) direction, please calculate the
stress in MPa at which yielding will occur. The critical resolved shear stress for this alloy
is 800 MPa. - Answer- d.
2155.6
Metals, ceramics, and polymers represent the major classes of materials. Which of
them can be manufactured in crystalline form?
Answers:
a. Metals
b. Polymers
c. Ceramics
