Explore topic-wise MCQs in Phase Transformation.

This section includes 14 Mcqs, each offering curated multiple-choice questions to sharpen your Phase Transformation knowledge and support exam preparation. Choose a topic below to get started.

1.

Assume the volume fraction 0.4 of particles all with a radius 3mm, the grain boundary energy is given as 6kJ/mm. Calculate the restraining force per unit area of boundary? (Approximately)

A. 1.2
B. 1.8
C. 2.4
D. 3.6
Answer» B. 1.8
Discussion
2.

Aluminium-killed steels contain aluminium nitride precipitates which stabilize the austenite grain size during heating.

A. False
B. True
Answer» C.
Discussion
3.

Stabilization of a fine grain size during heating at high temperatures requires__________

A. Large fraction of small particles
B. Small fraction of large particles
C. Large fraction of large particles
D. Small fraction of small particles
Answer» E.
Discussion
4.

Calculate the maximum grain size D max possible, if the radius of the spherical particle is 5mm and the volume fraction is given as 0.2?

A. 33.33mm
B. 66.66mm
C. 10mm
D. 38.33mm
Answer» B. 66.66mm
Discussion
5.

If there is a volume fraction f of particles all with a radius r the mean number of particles intersecting unit area of a random plane is_________

A. 2f/ r<sup>2</sup>
B. 5f/ r<sup>2</sup>
C. 3f/ r<sup>2</sup>
D. 3f/2 r<sup>2</sup>
Answer» E.
Discussion
6.

The nature of normal grain growth in the presence of a second phase deserves special consideration. The moving boundaries will be attached to the particles exert a pulling force on the boundary restricting its motion. Therefore if the boundary intersects the particle surface at 90 the particle will feel a pull of (2 r cos )*sin . This will be counterbalanced by an equal and opposite force acting on the boundary. As the boundary moves over the particle surface changes and the drag reaches a maximum value, this happens when becomes______

A. 90
B. 45
C. 60
D. 30
Answer» E.
Discussion
7.

There can be this growth of just a few grains to very large diameters. Such situation is known as_____

A. Unusual grain growth
B. Abnormal grain growth
C. Altered grain growth
D. Acceptable grain growth
Answer» C. Altered grain growth
Discussion
8.

Experimentally for finding the grain size we use the equation, D = Kt . Here K is the temperature dependent proportionality constant and n is a number less than 0.5 and this n can be taken as 0.5 under which circumstances?

A. Low temperature
B. High pressure
C. Impure metals
D. High temperature
Answer» E.
Discussion
9.

Surface grooving where grain boundaries intersect free surfaces leads to_______

A. Surface roughness
B. Smoothening
C. Texture
D. Increase in grain size
Answer» B. Smoothening
Discussion
10.

Coarsening is a process that can be considered quite identical to grain growth.

A. True
B. False
Answer» C.
Discussion
11.

Experimentally one can find the grain size as function of time. If the K value is given as 3mm/sec (temperature dependent proportionality constant) and n is 0.2. Find the grain diameter at t =2sec?

A. 8.76mm
B. 2.67mm
C. 3.45mm
D. 4.56mm
Answer» D. 4.56mm
Discussion
12.

Calculate the mean diameter of the grain at t=5sec, Assume the grain boundary energy and mobility are given as 5 Nmm-1 and 10mm3J-1s-1 respectively? (Assume the mean size of the grain at t=0 as 3mm)

A. 109mm
B. 1009mm
C. 10.9m
D. 9mm
Answer» C. 10.9m
Discussion
13.

The driving force or the rate of grain growth is given by_________ ( -surface energy, D- mean grain diameter, M-mobility)

A. v = k*M*(2 /D)
B. v = k + M*(2 /D)
C. v = k*M*(2D/ )
D. v = k*M*( /D)
Answer» B. v = k + M*(2 /D)
Discussion
14.

In a single-phase metal the rate at which the mean grain diameter D increases with time will depend on the ____________

A. Flow rate
B. Texture
C. Grain boundary size
D. Grain boundary mobility
Answer» E.
Discussion