MTL 200 Final Exam
Al2O3-Cr2O3 is same as ____'s _______ phase diagram and why? - correct answer-Ni-Cu,
isomorphous
- same crystal structure
- same charge
- pure vacancy substitution occurs since radii are almost equal
Diffusion driving force = ? - correct answer-Concentration gradient
Do silicates have a strong or weak bond? What kind of bond is it? - correct answer-strong
covalent bond
Given the crystal structure, what are the reflections present (RP)?
BCC
FCC
Simple Cubic - correct answer-RP
BCC: (h+k+l) even
FCC: h, k & l are all even or all odd
Simple Cubic: All
How do valences affect solubility in substitutional SS? - correct answer-other factors being
equal, a metal has more of a tendency to dissolve another metal of high valence than to
dissolve one of lower valency
How do you convert [UVW] to [uvtw]? - correct answer-u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
How does atomic size factor affect solubility in substitutional SS? - correct
answer-appreciable quantities of a solute may be accommodated in SS only when the
difference in radii is less than 15%, otherwise new phases form
How does crystal structure affect solubility in substitutional SS? - correct answer-crystal
structures must be the same for the metals
How does electronegativity factor affect solubility in substitutional SS? - correct answer-the
larger the difference in electronegativity in the elements, the greater the chance that they will
form an intermetallic compound instead of substitutional SS
How is an oxidation reaction forced in the reverse direction? - correct answer-using a
galvanic couple, galvanizing process and external DC power supply
How many atoms are in the BCC structure? - correct answer-2 atoms
, How many atoms are in the FCC structure? - correct answer-4 atoms
How many atoms are in the HCP structure? - correct answer-6 atoms
How many eutectic reactions are present in the MgO-Al2O3 system? - correct answer-2
eutectic reactions
If given a diffraction angle of 40 degrees, what value do you use in the Bragg's Law
equation? - correct answer-20 degrees (diffraction angle/2)
MgO-Al2O3 is similar to the ____ phase diagram for ____ and why? - correct
answer-eutectic, Pb-Mg
- different charges and atomic radii
- formation of two eutectics
The formula for grain size determination is n = 2^(G-1) = Nm(M/100)^2. What does each
variable represent? - correct answer-n = the average # of grains per square INCH at
magification 100X
G = ASTM grain size #
Nm = # grains per square inch at the magnification M
What 2 elements are silicates composed of? - correct answer-silicon and oxygen
What 2 factors determine the size of an ion? - correct answer-- coordination number
increases (# of neighboring oppositely charged particles increase as the radius increases)
- charge of ion (radius increases as # of electrons increases)
What are 1 example of elements with a Simple Cubic structure? - correct answer-Polonium
What are 2 condition for an atom to migrate? - correct answer-- an empty adjacent site
- sufficient energy to break bonds
What are 2 defects associated with grain boundaries? - correct answer-- tilt boundary
(aligned angle of disorientation)
- twist boundary (parallel angle)
- light mismatch between grains
What are 2 defects associated with twin boundaries? - correct answer-mirror lattice
symmetry
- due to atomic displacement form applied shear forces (BCC and HCP)
- due to annealing after deformation (FCC)
What are 2 examples of congruent transformation? - correct answer-allotropic
transformation, melting of PURE metal (fixed temperature)
What are 3 different kinds of microscopes and their magnifications? - correct answer--
optical: 2000X max magnification
- electron -> TEM: 1 000 000X, SEM: 10X-50 000X
Al2O3-Cr2O3 is same as ____'s _______ phase diagram and why? - correct answer-Ni-Cu,
isomorphous
- same crystal structure
- same charge
- pure vacancy substitution occurs since radii are almost equal
Diffusion driving force = ? - correct answer-Concentration gradient
Do silicates have a strong or weak bond? What kind of bond is it? - correct answer-strong
covalent bond
Given the crystal structure, what are the reflections present (RP)?
BCC
FCC
Simple Cubic - correct answer-RP
BCC: (h+k+l) even
FCC: h, k & l are all even or all odd
Simple Cubic: All
How do valences affect solubility in substitutional SS? - correct answer-other factors being
equal, a metal has more of a tendency to dissolve another metal of high valence than to
dissolve one of lower valency
How do you convert [UVW] to [uvtw]? - correct answer-u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
How does atomic size factor affect solubility in substitutional SS? - correct
answer-appreciable quantities of a solute may be accommodated in SS only when the
difference in radii is less than 15%, otherwise new phases form
How does crystal structure affect solubility in substitutional SS? - correct answer-crystal
structures must be the same for the metals
How does electronegativity factor affect solubility in substitutional SS? - correct answer-the
larger the difference in electronegativity in the elements, the greater the chance that they will
form an intermetallic compound instead of substitutional SS
How is an oxidation reaction forced in the reverse direction? - correct answer-using a
galvanic couple, galvanizing process and external DC power supply
How many atoms are in the BCC structure? - correct answer-2 atoms
, How many atoms are in the FCC structure? - correct answer-4 atoms
How many atoms are in the HCP structure? - correct answer-6 atoms
How many eutectic reactions are present in the MgO-Al2O3 system? - correct answer-2
eutectic reactions
If given a diffraction angle of 40 degrees, what value do you use in the Bragg's Law
equation? - correct answer-20 degrees (diffraction angle/2)
MgO-Al2O3 is similar to the ____ phase diagram for ____ and why? - correct
answer-eutectic, Pb-Mg
- different charges and atomic radii
- formation of two eutectics
The formula for grain size determination is n = 2^(G-1) = Nm(M/100)^2. What does each
variable represent? - correct answer-n = the average # of grains per square INCH at
magification 100X
G = ASTM grain size #
Nm = # grains per square inch at the magnification M
What 2 elements are silicates composed of? - correct answer-silicon and oxygen
What 2 factors determine the size of an ion? - correct answer-- coordination number
increases (# of neighboring oppositely charged particles increase as the radius increases)
- charge of ion (radius increases as # of electrons increases)
What are 1 example of elements with a Simple Cubic structure? - correct answer-Polonium
What are 2 condition for an atom to migrate? - correct answer-- an empty adjacent site
- sufficient energy to break bonds
What are 2 defects associated with grain boundaries? - correct answer-- tilt boundary
(aligned angle of disorientation)
- twist boundary (parallel angle)
- light mismatch between grains
What are 2 defects associated with twin boundaries? - correct answer-mirror lattice
symmetry
- due to atomic displacement form applied shear forces (BCC and HCP)
- due to annealing after deformation (FCC)
What are 2 examples of congruent transformation? - correct answer-allotropic
transformation, melting of PURE metal (fixed temperature)
What are 3 different kinds of microscopes and their magnifications? - correct answer--
optical: 2000X max magnification
- electron -> TEM: 1 000 000X, SEM: 10X-50 000X
