mse midterm 2

which one of the materials below has the highest electrical conductivity?
gold
polyethylene
polystyrene

gold

which types of materials can be reshaped by heating?
thermosets or thermoplastics

thermoplastics

reducing the grain size in materials
increases/ decreases/ does not influence yield strength

increases

as cold work (%CW) is increased...
tensile strength does what?

increases

poisson's ratio for the majority of materials lies within the following range
from -0.25 to 0.25
from 0.25 to 0.5

from 0.25 to 0.5

in the plot on the right, which materials has a higher ductility?

material 2 is more ductile than 1

in the plot, which material has a higher yield strength?

material 1 has a higher yield strength

an amorphous polymer may behave like...

first, a glass at low temperatures, then, a rubbery solid at intermediate temperatures (above
the glass transition temperature), and as a viscous liquid at high temperatures

which of the following correctly represents, for an amorphous polymer, a sequential change in mechanical state with increasing in temp?
a) rubbery solid, then transition to viscous liquid, then transition to glass
b) glass, then transition to rubbery solid, then transition to viscous liquid
c) rubbery solid, then transition to glass, then to viscous liquid
d) rubbery solid, then transition to viscous liquid

b) glass, then transition to rubbery solid, then transition to viscous liquid

For a given material the tensile strength is 250 MPa and a yield strength is 150 MPa. You start applying tensile stress and gradually increase this applied value. At which value of the applied stress does the onset of necking occur?

500 MPa
250 MPa
150 MPa
300 MPa

250

The direction of motion of a screw dislocation's line is ____ to the direction of an applied shear stress
a) perpendicular
b) parallel
c) 45 degrees

perpendicular

For a particular crystal structure, the slip plane is the plane having the
lowest or highest planar density

highest

You have Metal 1 with Young's modulus E1 and metal 2 with young's mod E2 = 2 * E1. You apply the same tensile stress to both metals. Assume that your deformation is elastic. the resulting tensile strain in metal 2 is...
the same
twice as large
twice as small

twice as small than the strain in metal 1

Yield strength is defined as a stress at which noticeable plastic deformation with e= 0.002 has occurred.
true
false

true

Which of the following is a point defect in ceramics representing a cation vacancy-cation interstitial pair?
a) frenkel defect
b) schottky defect
c) edge dislocation
d) screw dislocation

frenkel defect

Which of the following is a (are) ID defect(s)?
a) A Frenkel defect
b) A Schottky defect
c) An edge dislocation
d) A screw dislocation

edge and screw

How many slip systems are there in FCC crystal structure? 3 4 12 16

12

Which one of the following statements is true. Take into account that the Nitrogen is an interstitial impurity in Fe, whereas Cr is a substitutional impurity
a) diffusion coefficient for N in Fe at 750 C is higher than for Cr in Fe at 750
b) diffusion coefficient for N in Fe at 750 C is lower than for Cr in Fe at 750
c) diffusion coefficient for N in Fe at 750 C is equal to that for Cr in Fe at 750

a) diffusion coefficient for N in Fe at 750 C is higher than for Cr in Fe at 750

Increasing activation energy Qd in expression for diffusion coefficient, D
increases/ decreases/ does not affect

decreases

You have a material A with the tensile strength 300 MPa, a material B with the tensile strength 200 MPa, and a Material C with the tensile strength 50 MPa. Which one of these materials most likely has a highest hardness?
material A or B or C

A

For a given material the tensile strength is 200 MPa, and a yield strength is 100 MPa. You need to use this material with a factor of safety 2. What would be the maximum working tensile stress you can apply to this material
400 MPa
200 MPa
100 MPa
50 MPa

50 MPa

a) Draw a schematic of an engineering stress-engineering strain curves for Material A and Material B. Label both axes. You are given that Material A has a higher Young's modulus, higher tensile strength and a higher yield strength than material B. You also know that the material A is less ductile than the material B. On both curves, mark (1) tensile strength, (2) fracture point, (3) yield strength.

Which of the following is a (are) 1 D defect(s)?
a) A Frenkel defect
b) A Schottky defect
c) An edge dislocation
d) A screw dislocation

c) An edge dislocation
d) A screw dislocation

How does each of the following influence the tensile modulus of a semicrystalline polymer
(a) molecular weight decrease
(b) degree of crystallinity increase
(c) deformation of drawing
(d) annealing of an undeformed material
(e) annealing of a drawn material

A) non-direct influence, increase, decrease, decrease, decrease
B) non-direct influence, increase, increase, increase, decrease
C) non-direct influence, increase, decrease, increase, decrease
D) increase, decrease, decrease, increase, decrease

B) non-direct influence, increase, increase, increase, decrease

is it possible for three or more elements to form a solid solution?

yes

Does the grain-size number G increases or decreases with the decrease in the grain size

increase

which of the materials below has the highest electrical conductivity?
silver
silicon
polystyrene

silver

Which of the materials below has the lowest electrical conductivity?
a) Polyethylene
(b) Iron
(c) Aluminum Oxide
(d) Silicon

a) Polyethylene

For a screw dislocation, Burgers vector is perpendicular to the dislocation line
true or false

false

For an edge dislocation, Burgers vector is perpendicular to the dislocation line
true false

true

Which one of the following statements is true?

(a) Adding Ni to Cu increases its conductivity
(b) Adding Ni to Cu decreases its conductivity
(c) Adding Ni to Cu does not affect its conductivity

Which types of solid solutions do you know?

substitutional and interstitial

A cation vacancy-cation interstitial pair is called _____ defect

frenkel

A pair of cation and anion vacancies is called ______ defect

schottky

With the increase in temperature T, the vacancies concentration in metallic crystal structure
(a) increases
(b) decreases
(c) remains constant

increases

With the increase in temperature T, the concentration of the Shottky defects in a ceramic material
increases/ decreases/ remains constant

increases

The image on the right shows the inter-atomic force as a function of separation for two metals. Which one of the following statements is true?
(a) the atoms are more strongly bonded in metal 1 than 2
(b) the atoms are more strongly bonded in metal 2 than 1

(b) the atoms are more strongly bonded in metal 2 than 1

Which material from the list below has a lowest Young's modulus?
(a) Cu alloys
(b) Magnesium
(c) Graphite
(d) Polyester
(e) Carbon fibers
(f) Molybdenum

(d) Polyester

The σy marked on the plot on the right is called
tensile strength
yield strength
tensile stress
toughness

yield strength

In the plot on the right, which material has a higher ductility?
material 1 is more ductile than 2
material 2 is more ductile than 1

material 2 is more ductile than 1

In the plot given, which material has a larger Young's modulus?
(a) Young's modulus of material 1 is larger than Young's modulus of material 2
(b) Young's modulus of material 2 is larger than Young's modulus of material 1

(a) Young's modulus of material 1 is larger than Young's modulus of material 2

In the plot provided, which material has a larger toughness?
(a) material 1 has a larger toughness
(b) material 2 has a larger toughness

(b) material 2 has a larger toughness

young's modulus is defined as
ratio of stress over strain
ratio of strain over stress
stress multiplied by strain

ratio of stress over strain

what characteristic defines the resistance to permanently indenting the surface of the material?

hardness

Poisson's ratio is defined as
(a)ratio of a tensile strain over a lateral strain
(b)ratio of a lateral strain over a tensile strain
(c)ratio of a tensile strain over a lateral strain multiplied by "-1"
(d)ratio of a lateral strain over a tensile strain multiplied by "-1"

(d)ratio of a lateral strain over a tensile strain multiplied by "-1"

Poisson's ratio for the majority of the materials lies within the following range (choose the correct statement from the list below)
(a) from 0.25 to 0.5
(b) from 0 to 0.25
(c) from -0.1 to 0.1

(a) from 0.25 to 0.5

You have a material A with the tensile strength 100 MPa, a material B with the tensile strength 200 MPa, and a material C with the tensile strength 300 MPa. Which one of these materials most likely has a highest hardness?

Material C

engineering stress - strain plot