MatSci Exam 2 QUESTIONS AND ASNWERS YEAR 2025.
For impurities diffusing in solid materials, the diffusion rate will be [A] at higher
temperature, and will be [B] when the required activation energy is greater. -
✅✅Higher, Lower
Interstitial diffusion - ✅✅Motion of atoms from an interstitial position to a neighboring
one
Vacancy diffusion - ✅✅Motion of atoms from a normal lattice position to an adjacent
empty position
Steady-state diffusion - ✅✅The diffusion in which the diffusion flux is constant
Nonsteady-state diffusion - ✅✅Diffusion in which the concentration of species is
changing with time
T or F: The diffusion in solid material is similar to that in liquids. It happens because all
atoms are in random motion. - ✅✅False
T or F: For atoms diffusing in solid materials, they have to overcome energy barriers to
move one step at a time - ✅✅True
T or F: The diffusion flux in a material will be zero if the concentrations of all atoms are
uniform throughout the material - ✅✅True
T or F: The diffusion flux in a material will be zero if the temperature is uniform
throughout the material. - ✅✅False
What is the difference between diffusion in solid materials and that in liquids? - ✅✅In
liquids, diffusion is caused by random motion of all atoms. In solids, diffusion depends
on atoms moving along vacancy or interstitial sites, they have to overcome energy
barriers and move one step at a time.
Ductility - ✅✅Degree of plastic deformation at fracture
Hardness - ✅✅Resistance to localized plastic deformation
Resilience - ✅✅The maximum energy that can be absorbed by the material through
elastic deformation
, Toughness - ✅✅The maximum energy that can be absorbed by the material before
fracture
Stiffness - ✅✅The ratio between stress and strain in elastic deformation
Yield Strength - ✅✅Stress at which plastic deformation begins
Tensile Strength - ✅✅The maximum stress that the material can withstand under
tensile load
Poisson's Ratio - ✅✅The ratio between lateral strain and axial strain when the force
is along the axial direction
T or F: Materials with greater toughness will have greater hardness. - ✅✅False
T or F: Materials with greater elastic modulus will have greater stiffness. - ✅✅True
T or F: Materials with greater tensile strength will have greater hardness. - ✅✅True
T or F: Materials with greater toughness will have greater stiffness. - ✅✅False
What is the difference between elastic deformation and plastic deformation in a couple
of sentences. - ✅✅The material will return to its original size and shape after
removing the load that causes elastic deformation. The shape will permanently
changeunder plastic deformation.
Slip - ✅✅Motion of dislocation
Fatigue - ✅✅Failure of a material due to dynamic stresses
Creep - ✅✅Slow and permanent deformation of materials under constant stresses
Steel composed of iron and a small amount of carbon is a lot stronger than pure iron. -
✅✅Interstitial impurities dissolved in the host material can anchor dislocations and
restrict their motion.
When you cut a piece of metal, the edge of the piece is usually harder than the other
regions. - ✅✅A plastically deformed region will have more dislocations that hinder the
motion of nearby dislocations.
If you measure the hardness of metal at the same location twice using a hardness
tester, the second reading is larger than the first one. - ✅✅A plastically deformed
region will have more dislocations that hinder the motion of nearby dislocations.
For impurities diffusing in solid materials, the diffusion rate will be [A] at higher
temperature, and will be [B] when the required activation energy is greater. -
✅✅Higher, Lower
Interstitial diffusion - ✅✅Motion of atoms from an interstitial position to a neighboring
one
Vacancy diffusion - ✅✅Motion of atoms from a normal lattice position to an adjacent
empty position
Steady-state diffusion - ✅✅The diffusion in which the diffusion flux is constant
Nonsteady-state diffusion - ✅✅Diffusion in which the concentration of species is
changing with time
T or F: The diffusion in solid material is similar to that in liquids. It happens because all
atoms are in random motion. - ✅✅False
T or F: For atoms diffusing in solid materials, they have to overcome energy barriers to
move one step at a time - ✅✅True
T or F: The diffusion flux in a material will be zero if the concentrations of all atoms are
uniform throughout the material - ✅✅True
T or F: The diffusion flux in a material will be zero if the temperature is uniform
throughout the material. - ✅✅False
What is the difference between diffusion in solid materials and that in liquids? - ✅✅In
liquids, diffusion is caused by random motion of all atoms. In solids, diffusion depends
on atoms moving along vacancy or interstitial sites, they have to overcome energy
barriers and move one step at a time.
Ductility - ✅✅Degree of plastic deformation at fracture
Hardness - ✅✅Resistance to localized plastic deformation
Resilience - ✅✅The maximum energy that can be absorbed by the material through
elastic deformation
, Toughness - ✅✅The maximum energy that can be absorbed by the material before
fracture
Stiffness - ✅✅The ratio between stress and strain in elastic deformation
Yield Strength - ✅✅Stress at which plastic deformation begins
Tensile Strength - ✅✅The maximum stress that the material can withstand under
tensile load
Poisson's Ratio - ✅✅The ratio between lateral strain and axial strain when the force
is along the axial direction
T or F: Materials with greater toughness will have greater hardness. - ✅✅False
T or F: Materials with greater elastic modulus will have greater stiffness. - ✅✅True
T or F: Materials with greater tensile strength will have greater hardness. - ✅✅True
T or F: Materials with greater toughness will have greater stiffness. - ✅✅False
What is the difference between elastic deformation and plastic deformation in a couple
of sentences. - ✅✅The material will return to its original size and shape after
removing the load that causes elastic deformation. The shape will permanently
changeunder plastic deformation.
Slip - ✅✅Motion of dislocation
Fatigue - ✅✅Failure of a material due to dynamic stresses
Creep - ✅✅Slow and permanent deformation of materials under constant stresses
Steel composed of iron and a small amount of carbon is a lot stronger than pure iron. -
✅✅Interstitial impurities dissolved in the host material can anchor dislocations and
restrict their motion.
When you cut a piece of metal, the edge of the piece is usually harder than the other
regions. - ✅✅A plastically deformed region will have more dislocations that hinder the
motion of nearby dislocations.
If you measure the hardness of metal at the same location twice using a hardness
tester, the second reading is larger than the first one. - ✅✅A plastically deformed
region will have more dislocations that hinder the motion of nearby dislocations.
