MTL 200 UPDATED TEST GUIDE 2026
PROVEN SOLUTIONS DELIVERED
⫸ What is a polycrystalline? Answer: several crystals having
different crystal orientations
⫸ What is a grain boundary? Answer: the interface between two
grains or crystallites in a polycrystalline material
⫸ What is a non-crystalline? Answer: amorphous, no system
arrangements of atoms
⫸ What are the different forms of solid solutions (SS)? Answer:
Substitutional and Interstitial
⫸ What are the factors that affect the solubility of substitutional solid
solutions? Answer: - atomic size factor
- crystal structure
- electronegativity
- valence
⫸ How does atomic size factor affect solubility in substitutional SS?
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?
Answer: crystal structures must be the same for the metals
⫸ How does electronegativity factor affect solubility in substitutional
SS? 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 do valences affect solubility in substitutional SS? 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
⫸ What is the maximum allowable interstitial impurity? Answer:
less than 10%
⫸ What is the formula for approximate alloy density? Answer: p =
100/((C1/P1)+(C2/P2)+(C3/P3) etc)
⫸ What is the formula for alloy atomic weight? Answer: A =
100/((C1/A1)+(C2/A2)+(C3/A3) etc)
⫸ What is the Burger Vector? What is the magnitude equal to?
Answer: - magnitude and direction of the lattice distortion associated
with a dislocation
- will be the same at all points along its line
- magnitude equal to the interatomic spacing
, - neither parallel nor perpendicular to mixed dislocations
⫸ What is edge dislocation? What kind of grain boundary does it
have? Answer: - linear defect that centers on the line that is defined
along the end of the extra half-plane of atoms
- the dislocation line and burgers vector are perpendicular
- tilt boundaries
⫸ What is screw dislocation? What kind of grain boundary does it
have? Answer: - a shear stress that causes the slip of planes
- the dislocation line and burgers vector are parallel
- twist boundaries/distortion
⫸ What is mixed dislocation? Answer: most common types of
dislocations which involve neither screw nor edge dislocation
⫸ What are interfacial defects? Answer: include external surfaces,
grain boundaries (exist in polycrystalline materials) and stacking
faults
⫸ What is the external surface area dependent on? Answer: packing
planar density
⫸ What are 2 defects associated with grain boundaries? Answer: -
tilt boundary (aligned angle of disorientation)
- twist boundary (parallel angle)
PROVEN SOLUTIONS DELIVERED
⫸ What is a polycrystalline? Answer: several crystals having
different crystal orientations
⫸ What is a grain boundary? Answer: the interface between two
grains or crystallites in a polycrystalline material
⫸ What is a non-crystalline? Answer: amorphous, no system
arrangements of atoms
⫸ What are the different forms of solid solutions (SS)? Answer:
Substitutional and Interstitial
⫸ What are the factors that affect the solubility of substitutional solid
solutions? Answer: - atomic size factor
- crystal structure
- electronegativity
- valence
⫸ How does atomic size factor affect solubility in substitutional SS?
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?
Answer: crystal structures must be the same for the metals
⫸ How does electronegativity factor affect solubility in substitutional
SS? 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 do valences affect solubility in substitutional SS? 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
⫸ What is the maximum allowable interstitial impurity? Answer:
less than 10%
⫸ What is the formula for approximate alloy density? Answer: p =
100/((C1/P1)+(C2/P2)+(C3/P3) etc)
⫸ What is the formula for alloy atomic weight? Answer: A =
100/((C1/A1)+(C2/A2)+(C3/A3) etc)
⫸ What is the Burger Vector? What is the magnitude equal to?
Answer: - magnitude and direction of the lattice distortion associated
with a dislocation
- will be the same at all points along its line
- magnitude equal to the interatomic spacing
, - neither parallel nor perpendicular to mixed dislocations
⫸ What is edge dislocation? What kind of grain boundary does it
have? Answer: - linear defect that centers on the line that is defined
along the end of the extra half-plane of atoms
- the dislocation line and burgers vector are perpendicular
- tilt boundaries
⫸ What is screw dislocation? What kind of grain boundary does it
have? Answer: - a shear stress that causes the slip of planes
- the dislocation line and burgers vector are parallel
- twist boundaries/distortion
⫸ What is mixed dislocation? Answer: most common types of
dislocations which involve neither screw nor edge dislocation
⫸ What are interfacial defects? Answer: include external surfaces,
grain boundaries (exist in polycrystalline materials) and stacking
faults
⫸ What is the external surface area dependent on? Answer: packing
planar density
⫸ What are 2 defects associated with grain boundaries? Answer: -
tilt boundary (aligned angle of disorientation)
- twist boundary (parallel angle)
