Top 1000+ Solved Material Science MCQ Questions Answer

From 166 to 180 of 923

Q. On thermal excitation this                    defect may cause

a. vacancy

b. edge dislocations

c. screw dislocations

d. none of the above

  • a. vacancy

Q. The grain boundary area decreases when a polycrystalline material is heated

a. below recrystalliza tion temp.

b. above recrystalliza tion temp.

c. above room temp.

d. below 0.5 tm

  • b. above recrystalliza tion temp.

Q. Ideal crystals have

a. no imperfectio ns

b. real crystals

c. vaccancies

d. frenkel defects

  • a. no imperfectio ns

Q. The imperfections may be minimised by

a. thermal energy

b. making metal in fibre form

c. surface treatment

d. all of the above

  • d. all of the above

Q. Volume imperfections can be

a. twin

b. slip

c. stacking fault

d. noncrystalli ne regions

  • d. noncrystalli ne regions

Q. The cross slip occurs in :

a. climb up motion

b. screw dislocation

c. gliding motion

d. none of the above

  • b. screw dislocation

Q. .......... defects are inperfect point like region in a crystal.

a. line

b. point

c. edge

d. screw

  • b. point

Q. A ............is the simplest point defect and envolves a missing atom within a metal.

a. schottky

b. vacancy

c. line

d. dislocation

  • b. vacancy

Q. -------- imperfections involve vacancies of a pair ions of opposite charges.

a. frankel

b. schottky

c. dislocation

d. point

  • b. schottky

Q. The displacement distance for atoms around the dislocation is the---- --.

a. burger vector

b. screw

c. edge

d. point

  • a. burger vector

Q. -------- dislocation can glide and climb.

a. screw

b. edge

c. cross

d. atomic

  • b. edge

Q. -------- are difined as the irregularities in the structure of metals.

a. atomic

b. dislocation

c. point

d. vacancies

  • b. dislocation

Q. -------- dislocation plays an important role in crystal growth.

a. edge

b. screw

c. vacancies

d. schotty

  • b. screw

Q. Work hardening reduces:

a. malleability

b. hardness

c. toughness

d. ductility

  • d. ductility
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