Final Units

Question 1

What are the four methods of strengthening described in class?

Answer 1

strain hardening (cold working), grain size reduction, solid solution strengthening, precipitate hardening

Question 2

What property is sacrificed as a result of strengthening

Answer 2

Material ductility is sacrificed and materials are more brittle because the buildup of dislocations leads to cracks

Question 3

What is the driving force during heat treatment

Answer 3

Heat treatment’s driving force is that heat is decreasing the number of dislocations, thereby reduction in strain energy.

Question 4

What are the stages in heat treatment

Answer 4

Heat treatment stages are, recovery, recrystallization, and crystal growth respectively.

Question 5

What does bioinert mean

Answer 5

No toxic/tetrogenic/carcinogenic immune response from the body

Question 6

What does bioresuable mean?

Answer 6

Undergoes degradation in the body

Question 7

What does bioactive mean

Answer 7

Produces a targeted biological response

Question 8

What does xenograph mean

Answer 8

Animal based donor for an organ Advantages: Recovery of lost function and larger donor pool but possibility of immune rejection

Question 9

What is the characteristic of a ductile fracture

Answer 9

Ductile fractures have a lot of plastic deformation and slow crack propogation - large elasticity and area reduction before fracture

Question 10

What is the characteristic of a brittle fracture

Answer 10

Brittle fractures have little plastic deformation and fast crack propogation - little ductility and area reduction before fracture

Question 11

What’s the term for very ductile materials

Answer 11

Elastomers

Question 12

What’s the term for moderately ductile materials

Answer 12

Alloys

Question 13

What’s the term for very unductile and not brittle materials

Answer 13

Ceramics

Question 14

What are the stages of fracture?

Answer 14

Necking, void formation, void growth, crack propogation. Keep in mind that flow acts as stress concentrators.

Question 15

At a crack, the sharper the crack

Answer 15

The higher stress at the crack tip (considered a stress concentrator)

Question 16

What does crack propogation depend on

Answer 16

Temperature, strain rate, and microstructure.

Question 17

Explain all of the variables associated with fatigue graphs

Answer 17

S is the amplitude or stress amplitude determined by the delta between the maximum and minimum.

Question 18

Explain all of the variables associated with fatigue graphs

Answer 18

S is the amplitude or stress amplitude determined by the delta between the maximum and minimum. N is the number of cycles to failure at a particular stress amplitude S. The range of stress is the maximum - minimum.

Question 19

Explain all of the variables associated with fatigue graphs

Answer 19

S is the amplitude or stress amplitude determined by the delta between the maximum and minimum. N is the number of cycles to failure at a particular stress amplitude S. The range of stress is the maximum - minimum. While mean stress is the max and min averaged out.

Question 20

What are some ways you can improve for fatigue

Answer 20

1. Impose compressive surface stress 2. Remove stress concentrators by design.

Question 21

What are some ways you can improve for fatigue

Answer 21

1. Impose compressive surface stress 2. Remove stress concentrators by design.

Question 22

What properties are independent of size and geometry of the system

Answer 22

Resistivity and conductivity are independent of size and geometry.

Question 23

What does mattheisen’s rule suggest

Answer 23

presence of imperfections will increase resistivity, notably from dislocations, impurity atoms, and vacancies.

Question 24

Resistivity increases with

Answer 24

temperature, wt% measurement of impurity, and % cold working (thermal)