MTE 271 TEST 2 QUESTIONS AND
ANSWERS ALL CORRECT
What type of defect is a void? - Answer- 3-D
What type of defect is a surface? - Answer- 2-D
A Burger's vector completes the loop around a dislocation. True or False? - Answer-
True
What is NOT a type of dislocation?
a.) Edge
b.) Screw
c.) Mixed
d.) Burger - Answer- Burger (d.)
What type of defect is a dislocation? - Answer- 1-D
Diffusion is faster in a BCC crystal than an HCP crystal. True or False? - Answer- True
Why is diffusion slower for Fe in γ-Fe than C in α-Fe?
a.) Substitutional, higher packing factor (FCC)
b.) Interstitial, lower packing factor (BCC) - Answer- Substitutional, Higher packing
factor (FCC) (a.)
Interstitial diffusion requires vacancies to occur. True or False? - Answer- False
Diffusion has a _____________ relationship with temperature. - Answer- Exponential
Fick's First Law is time dependent. True or False? - Answer- False
Mass flux has the unites of mass per cross-sectional area per unit time : kg / (m² × s).
True or False? - Answer- True
Fick's Second Law has a ____________ dependence - Answer- Error Function
Point Defects [ 0-D ] : - Answer- Vacancy atoms, Interstitial Solute, and Substitutional
Solute
, Line Defects [ 1-D ] : - Answer- Dislocations
Planar Defects [ 2-D ] : - Answer- Grain Boundaries, Phase Boundaries, and Twin
Boundaries
Volume Defects [ 3-D ] : - Answer- Cracks, Voids, and other phases
Hume-Rothery Rules for Forming a Solid Solution:
(If one or more of these rules are violated, only partial solubility is possible) - Answer-
1.) < 15% difference in atomic radii
2.) The same crystal structure
3.) Similar electronegativity (i.e., ability of an atom to attract an electron)
4.) Same (or similiar) Valence
Vacancy - Answer- A vacant or empty lattice site
Equilibrium concentration varies with ______________ - Answer- Temperature
A charge balance is not always required for every point defect introduced in an ionic
solid. True or False? - Answer- False
Localized disruptions in otherwise perfect atomic or ionic arrangements in a crystal
structure are called ________________ - Answer- Point Defects
The equation used for determining the number of vacancies per cm³ is n.v = n ( -Q.v /
(RT) ). True or False? - Answer- False
A _______________ is a vacancy-interstitial pair formed when an ion jumps from a
normal lattice point to an interstitial site and leaves behind a vacancy. - Answer- Frenkel
Defect
A(n) __________________ dislocation is illustrated by slicing partway through a perfect
crystal, spreading the crystal apart, and partly filling the cut with an extra half plane of
atoms. - Answer- Edge
BCC metals tend to have _____________ and _____________ compared to FCC
metals. - Answer- Higher Strengths and Lower Ductilities
Increasing the number of grains or reducing the grain size of a metallic material causes
grain-size ______________. - Answer- Strengthening
The process of progressively breaking and reforming bonds requires far more energy
than the energy that would be required to instantaneously break all of the bonds across
a slip plane.
True or False? - Answer- False
ANSWERS ALL CORRECT
What type of defect is a void? - Answer- 3-D
What type of defect is a surface? - Answer- 2-D
A Burger's vector completes the loop around a dislocation. True or False? - Answer-
True
What is NOT a type of dislocation?
a.) Edge
b.) Screw
c.) Mixed
d.) Burger - Answer- Burger (d.)
What type of defect is a dislocation? - Answer- 1-D
Diffusion is faster in a BCC crystal than an HCP crystal. True or False? - Answer- True
Why is diffusion slower for Fe in γ-Fe than C in α-Fe?
a.) Substitutional, higher packing factor (FCC)
b.) Interstitial, lower packing factor (BCC) - Answer- Substitutional, Higher packing
factor (FCC) (a.)
Interstitial diffusion requires vacancies to occur. True or False? - Answer- False
Diffusion has a _____________ relationship with temperature. - Answer- Exponential
Fick's First Law is time dependent. True or False? - Answer- False
Mass flux has the unites of mass per cross-sectional area per unit time : kg / (m² × s).
True or False? - Answer- True
Fick's Second Law has a ____________ dependence - Answer- Error Function
Point Defects [ 0-D ] : - Answer- Vacancy atoms, Interstitial Solute, and Substitutional
Solute
, Line Defects [ 1-D ] : - Answer- Dislocations
Planar Defects [ 2-D ] : - Answer- Grain Boundaries, Phase Boundaries, and Twin
Boundaries
Volume Defects [ 3-D ] : - Answer- Cracks, Voids, and other phases
Hume-Rothery Rules for Forming a Solid Solution:
(If one or more of these rules are violated, only partial solubility is possible) - Answer-
1.) < 15% difference in atomic radii
2.) The same crystal structure
3.) Similar electronegativity (i.e., ability of an atom to attract an electron)
4.) Same (or similiar) Valence
Vacancy - Answer- A vacant or empty lattice site
Equilibrium concentration varies with ______________ - Answer- Temperature
A charge balance is not always required for every point defect introduced in an ionic
solid. True or False? - Answer- False
Localized disruptions in otherwise perfect atomic or ionic arrangements in a crystal
structure are called ________________ - Answer- Point Defects
The equation used for determining the number of vacancies per cm³ is n.v = n ( -Q.v /
(RT) ). True or False? - Answer- False
A _______________ is a vacancy-interstitial pair formed when an ion jumps from a
normal lattice point to an interstitial site and leaves behind a vacancy. - Answer- Frenkel
Defect
A(n) __________________ dislocation is illustrated by slicing partway through a perfect
crystal, spreading the crystal apart, and partly filling the cut with an extra half plane of
atoms. - Answer- Edge
BCC metals tend to have _____________ and _____________ compared to FCC
metals. - Answer- Higher Strengths and Lower Ductilities
Increasing the number of grains or reducing the grain size of a metallic material causes
grain-size ______________. - Answer- Strengthening
The process of progressively breaking and reforming bonds requires far more energy
than the energy that would be required to instantaneously break all of the bonds across
a slip plane.
True or False? - Answer- False
