Mechanical Behaviour and Testing of Materials Practice Test 3

1. What is the strength of the Burgers vector for dislocations in BCC structure?

a/√2

a/3

3a/√2

a√3/2

2. Which term is used for the line which lies between the slipped and unslipped regions?

Dislocation line

Grain boundary

Slip line

Free surface

3. The force of attraction or repulsion _____ with decreasing distance of separation.

remains constant

decreases

increases

first increases and then decreases

4. Elastic energy of a dislocation is _____ the Burgers vector.

Proportional to the square of

Directly proportional to

Proportional to the square root of

Not dependent on

5. From annihilation of dislocations, total energy of system _____

increases

remains constant

first increases and then decreases

decreases

6. Below the edge of an extra half plane of edge dislocation, bonds are broken.

False

True

7. Match the following?

i-s, ii-r, iii-q, iv-p

i-r, ii-s, iii-p, iv-q

i-r, ii-s, iii-q, iv-p

i-s, ii-r, iii-p, iv-q

8. Lack of symmetry in crack shows anisotropy in a material.

False

True

9. What is the order of core energy?

3.0 – 10 eV

0.5 – 1.5 eV

0.1 – 1.0 eV

2.0 – 4.0 eV

10. Which statement is false?

Two edge dislocations of the same sign on parallel slip planes repel each other if ϴ<45°

Two edge dislocations of the same sign on parallel slip planes attract each other if ϴ<45°

Dislocations of same sign on the same slip plane repel each other

Dislocations of opposite sign on the same slip plane attract each other