1. Twin or Twinning is a category of _______
a) Point imperfections
b) Line imperfections
c) Volume imperfections
d) Surface imperfections
Explanation: A twin boundary is a two-dimensional imperfection (surface imperfection), but the entire twin is a category of volume imperfections.
2. As the grain size of a meal increases, its strength ________
a) Decreases
b) Increases
c) Remains constant
d) No effect of grain size on strength
Explanation: Strength of a metal is directly proportional to its ability resist plastic deformation, thus resisting its dislocation movement. As one can relate that, more the number of grain boundaries (fine is the grain size), more is the obstruction to the movement of dislocation, thus more is the strength of a metal. So, if grain size increases, its strength decreases. This phenomenon can be best understood with the help of Hall-Petch relation.
3. As the grain size of a meal increases, its ductility ________
a) Decreases
b) Increases
c) Remains constant
d) No effect of grain size on strength
Explanation: Fine the grain size (lower the grain size), more is the number of grain boundaries, thus more is the yield strength, thus more is the ductility. So, if grain size increases, its ductility decreases.
4. Phenomenon of cross slip occurs in ________
a) Point imperfections
b) Line imperfections
c) Volume imperfections
d) Surface imperfections
Explanation: When we apply a stress, it causes screw dislocations to move from one slip plane to another slip plane, which is known as its cross slip. Cross slip is one of the primary mechanisms that causes plastic deformation in metals.
5. Resistance of a material against any external force is termed as _______________
a) Stiffness
b) Malleability
c) Strength
d) Hardness
Explanation: Strength is that mechanical property of a material by virtue of which it resists change in its dimension shape and any failure by application of any external force
6.The property of a material to resist any elastic deformation is termed as ____________
a) Stiffness
b) Hardness
c) Malleability
d) Strength
Explanation: The ability of a material or shape to resist elastic deflection is termed as stiffness of that material.
7. Resistance developed by surface of any material is known as ____________
a) Strength
b) Hardness
c) Stiffness
d) Creep
Explanation: Hardness is a surface property. Resistance developed by surface of any material is known as hardness.
8. Permanent deformation of material with respect to time due to constant load and variable temperature is termed as ____________
a) Elasticity
b) Isotropy
c) Hardness
d) Creep
Explanation: Creep is time and temperature dependent phenomenon. With the passage of time and other environmental condition, material may lead to fracture point.
9. Material having same identical values a property in all directions can be termed as ____________
a) Creep
b) Anisotropy
c) Isotropy
d) Orthotropic
Explanation: Isotropic materials have the same property in all directions. Crystalline substance is isotropic in nature.
10. Property by virtue of which material can absorb strain energy without plastic deformation is called ___________
a) Creep
b) Anisotropy
c) Resilience
d) Fatigue
Explanation: Resilience is the strain energy absorbed of a material without undergoing a plastic deformation.