Flashcards in Exam 2 Deck (56):

1

##
Which of the materials below has the lowest electrical resistivity?

polypropylene, copper, titanium dioxide, silicon

### copper

2

## A pair of cation vacancy-anion vacancy is called:

### Schottky defect

3

##
Which of the following is a 2D defect?

Frenkel defect, Schottky defect, edge dislocation, screw dislocation, grain boundary

### grain boundary

4

##
Which one of the following statements is true?

adding Ni to Cu increases its resistivity

adding Ni to Cu decreases its resistivity

adding Ni to Cu does not affect its resistivity

### adding Ni to Cu increases its resistivity

5

## As temperature increases, the diffusion coefficient D:

### increases

6

##
Which one of the following statements is true for the non steady-state diffusion:

both concentration and flux do not depend on time

concentration depends on time but flux does not

concentration does not depend on time but flux does

both concentration and flux depend on time

### both concentration and flux depend on time

7

##
Which one of the following statements is true for the steady-state diffusion:

both concentration and flux do not depend on time

concentration depends on time but flux does not

concentration does not depend on time but flux does

both concentration and flux depend on time

### both concentration and flux do not depend on time

8

##
C(o) in the solution of the Fick's Second Law fo non steady-state condition is:

initial concentration inside a sample

initial concentration at the samples' surface at time 0

final concentration at the sample's surface

final concentration inside the sample

### initial concentration inside a sample

9

##
Poisson's ration is defined as:

ratio of a lateral strain over a tensile strain

ratio of a tensile strain over a lateral strain

ratio of a lateral strain over a tensile strain multiplied by -1

ratio of a tensile strain over a lateral strain multiplied by -1

### ratio of a lateral strain over a tensile strain multiplied by -1

10

##
For a given material with a tensile strength is 480 MPa and a yield strength is 240 MPa. You need to use this material in a device with the factor of safety N=3. What would be the maximum working load allowed for this material?

160 MPa

240 MPa

80 MPa

480 MPa

### 80 MPa

11

##
As the impurity concentration in solid solution of a metal is increased, the tensile strength:

decreases

increases

remains unchanged

### increases

12

## As %CW in metallic alloy is increased

### yield strength increases and ductility decreases

13

## As %CW in metallic alloy is increased

### yield strength increases and tensile strength increases

14

##
A metal having a crystal structure with many operable slip systems will be relatively:

ductile

brittle

### ductile

15

## What type of point defects do you know?

### vacancies, interstitials, substitutional

16

## How does the number of vacancies change with increasing temperature?

### increases

17

## Two metals, A and B; both metals have FCC crystal structures. Metal A has an atomic radius of 0.3 nm and metal B has an atomic radius of 0.12 nm. Can these two metals form a complete substitution solid solution ( 0 % -100 % concentration)?

### no, the radius is > 15%

18

## Two metals, A and B. Metal A has FCC and metal B has BCC crystal structure. Metal A has an atomic radius of 0.121 nm and metal B has an atomic radius of 0.122 nm. Can these two metals form a a complete substitution solid solution (0 % -100 % concentration)?

### no, they have different crystal structures

19

## T/F: Two metals with similar electronegativity values can form substitutional solution

### true

20

##
Which of the materials below has the highest electrical conductivity:

silver

silicon

polystyrene

### silver

21

##
Which of the materials below has the lowest electrical conductivity:

iron

silicon

polyethylene

aluminum oxide

### polyethylene

22

## If a concentration of impurities increases electrical resistivity of a metal:

### increases

23

## If temperature increases electrical conductivity of a metal:

### decreases

24

##
Which of the following is a (are) 0D defect(s) in ceramics?

Schottky defect, screw dislocation, Frenkel defect, grain boundary, edge dislocation

### Schottky defect and Frenkel defect

25

## A cation vacancy-cation interstitial pair is called:

### Frenkel defect

26

##
Which of the following is a (are) 1D defect(s)?

Frenkel defect

grain boundary

Schottky defect

edge dislocation

screw dislocation

### edge dislocation and screw dislocation

27

## For a screw dislocation Burgers vector is:

### parallel to the dislocation line

28

## For an edge dislocation Burgers vector is:

### perpendicular to the dislocation line

29

##
Which of the following is a (are) 3D defect(s)?

terrace, kink, Frenkel defect, edge dislocation, adatom, ledge, screw dislocation, grain boundary, Schottky defect

### terrace, kink, adatom, and ledge

30

## If G-number is larger the corresponding grain size is:

### smaller

31

##
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

-Diffusion coefficient for N in Fe at 700°C is higher than that for Cr in Fe at 700°C

-Diffusion coefficient for N in Fe at 700°C is lower than that for Cr in Fe at 700°C

-Diffusion coefficient for N in Fe at 700°C is equal/similar to that for Cr in Fe at 700°C

### diffusion coefficient for N in Fe at 700°C is higher than that for Cr in Fe at 700°C

32

## You have a concentration gradient dB(x)/dx. What is the direction of the flux of species B:

### from high values of B to low values of B

33

## Increasing activation energy Q(D) in expression for diffusion coefficient, D,

### decreases D

34

## T/F: The first Fick's low postulates a linear dependency between concentration gradient and flux

### true

35

## What type(s) of diffusion do you know?

### vacancy diffusion and interstitial diffusion

36

## Engineering stress is calculated by

### dividing applied load by initial cross-section area of a sample

37

## Engineering strain is

### relative (to the original length) change of the sample's elongation

38

## For two samples (one of larger and one of smaller initial cross-section area) made of the same material if the applied stress is the same

### the resulting strain will be the same

39

## Poisson's ratio for the majority of the materials lies within the following range

### from .25 to .5

40

##
Which material from the list below has a lowest Young’s modulus?

polyester, Cu alloys, carbon fibers, molybdenum, magnesium

### polyester

41

## The σ(y) value marked on the plot is called

### yield strength

42

## Young's modulus is defined as

### ratio of stress over strain

43

## How elastic modulus calculated using true stress and strain related to the one calculated using engineering values

### different, but almost the same for small strain value

44

## The direction of motion of a screw dislocation's line is ______ to the direction of an applied shear stress.

### perpendicular

45

## The process by which plastic deformation is produced by dislocation motion that is called ________.

### slip

46

## For a particular crystal structure, the slip direction is the direction in the slip plane having the

### highest linear density

47

## As the impurity concentration in solid solution of a metal is increased, the tensile strength

### increases

48

## T/F: After an edge dislocation has passed through some region of a crystal, the atomic arrangement of that region is disordered

### false

49

## A metal having a crystal structure with many operable slip systems will be relatively

### ductile

50

## Relative to the direction of an applied shear stress, the direction of motion of an edge dislocation's line is ______.

### parallel

51

## T/F: Reducing the grain size of a metal increases its yield strength

### true

52

## T/F: Reducing the grain size of a metal increases its ductility

### false

53

## For a particular crystal structure, the slip plane is the plane having

### the highest planar density

54

## Which of the following correctly represents, for an amorphous polymer, the sequential change in mechanical state with increasing temperature?

### glass, then transition to rubbery solid, then transition to viscous liquid

55

## How does the decrease in molecular weight influence a tensile modulus of a polymer?

### no direct influence

56