EGN 3365 Exam 2

studied byStudied by 63 people
5.0(1)
get a hint
hint
<p>The given stress-strain graph represents?</p>

The given stress-strain graph represents?

1 / 76

Tags and Description

77 Terms

1
<p>The given stress-strain graph represents?</p>

The given stress-strain graph represents?

Elastic then plastic deformation

New cards
2
<p>What does the figure represent?</p>

What does the figure represent?

Simple compression

New cards
3
<p>Which material has the highest toughness?</p>

Which material has the highest toughness?

Material 2

New cards
4

For an engineering strain of 1, calculate percentage elongation (ductility) of the specimen?

100

New cards
5
<p>A specimen of copper having a rectangular cross-section 15.2 mm X 19.1 mm  is pulled in tension with 44,500 N  force, producing only elastic deformation. Calculate the resulting strain. ( Elastic modulus of copper = 110 GPa)</p>

A specimen of copper having a rectangular cross-section 15.2 mm X 19.1 mm  is pulled in tension with 44,500 N  force, producing only elastic deformation. Calculate the resulting strain. ( Elastic modulus of copper = 110 GPa)

1.39 x 10^-3

New cards
6
<p>Ductility is the amount of plastic deformation at failure.</p><p>From the given graph below, determine which line represent a material with high ductility and which line represent a material with low ductility.</p>

Ductility is the amount of plastic deformation at failure.

From the given graph below, determine which line represent a material with high ductility and which line represent a material with low ductility.

Blue line: Low ductility.

Green line: High ductility.

New cards
7
<p>For some metal alloy, the true stress of 345 MPa produces a plastic true strain of 0.02. How much does a specimen of this material elongate when true stress of 415 MPa is applied if the original length is 500 mm? Assume a value of 0.22 for the strain-hardening exponent, n.</p>

For some metal alloy, the true stress of 345 MPa produces a plastic true strain of 0.02. How much does a specimen of this material elongate when true stress of 415 MPa is applied if the original length is 500 mm? Assume a value of 0.22 for the strain-hardening exponent, n.

23.7mm

New cards
8

Poisson's ratio for metals, ceramics and polymers is in the range:

0.15 < v <= 0.5

New cards
9

Deformation of a sample to an engineering strain of 2 means that the sample is ___________ its original length.

A. Half

B. Twice

C. Three times

D. 2% longer than

Three times

New cards
10
<p>What best describes the figure?</p><p>A. Not an example of diffusion</p><p>B. Left: before diffusion, right: after diffusion</p><p>C. Left: after diffusion, right: before diffusion</p><p>D. None of the above</p>

What best describes the figure?

A. Not an example of diffusion

B. Left: before diffusion, right: after diffusion

C. Left: after diffusion, right: before diffusion

D. None of the above

Left: before diffusion; right: after diffusion

New cards
11

What is diffusion

Mass transport by atomic motion

New cards
12

Atoms tend to _____________ from regions of _____________ concentration to regions of _____________ concentration.

Migrate, high, low

New cards
13

What is self-diffusion?

Migration of host atoms in pure metals

New cards
14
<p>What is the derivation of the equation relating the diffusion coefficients at two temperatures T1 and T2, given that:</p>

What is the derivation of the equation relating the diffusion coefficients at two temperatures T1 and T2, given that:

D₂ = D₁exp [-Qd/R(1/T2-1/T2)]

New cards
15

At 300°C the diffusion coefficient and activation energy for Cu in Si are

D₁ (300°C) = 7.8 × 10⁻⁻¹¹ m²/s

Qd = 41.5 kJ/mol

Compute the diffusion coefficient D₂ at 400°C.

28.46 × 10⁻⁻¹¹ m²/s

New cards
16

Non-steady state diffusion is a function of:

Time and position

New cards
17

Fick’s first law of diffusion is applicable to

Steady state diffusion

New cards
18

What’s Fick’s second law of diffusion?

dC/dt = D d²C/dx²

New cards
19

What's Fick’s first law of diffusion?

J = −D dC/dx

New cards
20

What’s the relationship between the diffusion coefficient and temperature?

Increases with increasing temp

New cards
21

What is interdiffusion?

Diffusion of atoms of one material into another material

New cards
22

Diffusion rate of vacancy diffusion depends on

Number of vacancies, activation energy

New cards
23

interstitial diffusion

smaller atoms diffuse between adjacent atoms, faster than vacancy diffusion

New cards
24

Case hardening is an example of _________ diffusion

Interstitial

New cards
25

case hardening

outer surface is hardened by diffusing carbon atoms into surface

New cards
26

Doping

adding impurities to a semiconductor to increase conductivity

New cards
27

Process of doping

  1. P rich layers on surface

  2. Heat it

  3. Doped semiconductor regions

New cards
28

Diffusion is faster for

open crystal structures, materials with secondary bonding, smaller diffusing atoms, lower density materials

New cards
29

Tensile load (pulling)

If a specimen is being elongated or extended

New cards
30

Compressive load (pushing)

Specimen is compressed or contracted

New cards
31

Deformation

Change in dimension

New cards
32

shear forces

Parallel to cross sectional area

New cards
33

Plastic deformation

permanent change in shape by bending and folding

New cards
34

Elastic deformation

material returns to original state when stress is removed

New cards
35

Common states of stress

Simple tension, torsion, simple compression, bi-axial tension, hydrostatic compression

New cards
36

Yield strength

point where the material begins to plastically deform

New cards
37

Toughness

the ability of a material to resist fracture

New cards
38

Hardness

resistance to localized surface deformation and compressive stresses

New cards
39

Resilience

Ability of a material to store energy

New cards
40

Ductility

amount of plastic deformation at failure

New cards
41

Engineering stress

tensile, shear

New cards
42

Engineering strain

tensile, lateral, shear

New cards
43

Percent elongation

the total percent increase in length of a specimen during the tensile test

New cards
44

Dislocation

A defect where atoms are misaligned around it

New cards
45

Edge dislocation

extra half plane of atoms inserted into a crystal structure

New cards
46

Dislocation line

The line where dislocations happen

New cards
47

Screw dislocation

lattice plane shifts similar to a spiral staircase

New cards
48

Burgers vector

measure of lattice distortion

New cards
49

Twin boundary

a reflection of atom positions across the twin plane

New cards
50

Solidification

Result of casting molten material

New cards
51

Grain boundaries

Regions between grains (crystals)

New cards
52

Point defects

vacancy, interstitial atoms, substitutional atoms

New cards
53

Vacancies are

vacant atomic sites

New cards
54

Dislocations move when

Stresses are applied

New cards
55

A catalyst ____________ the rate is a chemical reaction without being consumed

Increases

New cards
56

Dislocation types include

Edge, screw, and mixed

New cards
57

two diffusion mechanisms

vacancy and interstitial

New cards
58

The applied mechanical force is normalized to

Stress

New cards
59

The degree of deformation is normalized to

strain

New cards
60

Elastic deformation is

nonpermanent and reversible

New cards
61

Plastic deformation is

permanent and nonrecoverable

New cards
62

Stiffness

a material's resistance to elastic deformation

New cards
63

Strength

A materials resistance to plastic deformation

New cards
64

In an optical microscope, grain boundaries appear as white lines after the surface is prepared by etching. T/F

false

New cards
65

According for Fick’s first law, the concentration of diffusing species is a function of both time and position. T/F

false

New cards
66

D_interstitial << D_substitutional

T/F

false

New cards
67

In edge dislocation, burger’s vector is perpendicular to dislocation line. T/F

true

New cards
68

Diffusion coefficient _________ with increasing temperature

increases

New cards
69

What are the interfacial defects?

twin boundaries, grain boundaries, stacking faults

New cards
70

I can observe individual atoms using an optical microscope. T/F

false

New cards
71

What’s an example to processing using diffusion

case hardening

New cards
72

Interstitial diffusion is more rapid than vacancy diffusion. T/F

true

New cards
73

Equiaxed grains are

Roughly the same dimension in all directions

New cards
74

Columnar grains are

grains elongated in one direction

New cards
75

Rate of diffusion is __________ of time

independent

New cards
76

Diffusion is ____________ of time

dependent

New cards
77

What are the 5 interfacial defects?

external surfaces, phase boundaries, optical boundaries, twin boundaries, stacking faults

New cards

Explore top notes

note Note
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 26 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 27 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 42 people
Updated ... ago
5.0 Stars(5)
note Note
studied byStudied by 798 people
Updated ... ago
5.0 Stars(1)

Explore top flashcards

flashcards Flashcard29 terms
studied byStudied by 38 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard109 terms
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard28 terms
studied byStudied by 4 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard35 terms
studied byStudied by 24 people
Updated ... ago
4.6 Stars(5)
flashcards Flashcard20 terms
studied byStudied by 1 person
Updated ... ago
5.0 Stars(1)
flashcards Flashcard138 terms
studied byStudied by 10 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard43 terms
studied byStudied by 19 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard26 terms
studied byStudied by 94 people
Updated ... ago
5.0 Stars(1)