GATE MT topic:materials-science PYQs & Answers — Page 18

Questions 171–180 of 650. Imported answers require independent review unless marked reviewed.

The constitutional undercooling condition for a hypothetical binary alloy of A with solute B during solidification is shown in the figure along with its binary phase diagram. Based on these two schematics, one can conclude that the solute concentration in region X will be __________ the average composition of the initial liquid phase.

Diagram for Metallurgical Engineering question 41

Your answerChoose one option.

less than

greater than

same as

independent of

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The microstructures of a quenched steel tempered at three temperatures

for a fixed time are schematically illustrated. The solid circles represent cementite particles in ferrite matrix;

and

are average radii of cementite particles, and

and

are volume fractions of cementite at temperatures

and

, respectively. If the cementite in steel is more noble than ferrite, then which one of the three microstructures will have the highest corrosion rate when exposed to an aqueous solution of 3.5 wt. % NaCl?

Diagram for Metallurgical Engineering question 42

Your answerChoose one option.

Microstructure at

Independent of microstructure

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An isotropic metallic cuboid block shown in the figure has a coefficient of linear thermal expansion

, Young’s modulus

and Poisson’s ratio

. The dimensions of the cuboid are

and

in the X, Y and Z directions, respectively. It is rigidly constrained against expansion in the X direction. However, it is free to expand in the Y and Z directions. It is initially stress-free. Subsequently, it is heated so that its temperature increases by

. What would be the CHANGE in the dimension of the cuboid in the Y direction?

Assume linear elasticity, and that thermal as well as mechanical strains are infinitesimally small.

Diagram for Metallurgical Engineering question 43

Your answerChoose one option.

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Match the entries in Column I with the stacking sequences of the close-packed planes listed in Column II.

Column I P. Face centered cubic (FCC) structure Q. Intrinsic stacking fault in FCC R. Across an annealing twin boundary in FCC S. Hexagonal close-packed structure

Column II

ABCABC

ABABAB

ABCACBC

ABCABCABCBA

Your answerChoose one option.

P – 1, Q – 3, R – 4, S – 2

P – 2, Q – 3, R – 1, S – 4

P – 3, Q – 1, R – 4, S – 2

P – 2, Q – 4, R – 1, S – 3

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Which one of the following graphs represents Griffith’s criterion for the growth of a crack in a brittle isotropic infinite large plate with a center crack?

In the graph,

is the magnitude of the total strain energy released (shown by solid curve) and

is the total surface energy (shown by dashed line) and

is the critical crack length (shown by downward arrow) at which the crack starts growing. The tangent to the

curve parallel to the

line is shown by the dotted line.

Your answerChoose one option.

Diagram for Metallurgical Engineering question 45

Diagram for Metallurgical Engineering question 45 (figure 2)

Diagram for Metallurgical Engineering question 45 (figure 3)

Diagram for Metallurgical Engineering question 45 (figure 4)

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For rolling of slabs, determine the correctness or otherwise of the following Assertion [a] and Reason [r].

Assertion [a]: Grooves are made on the surface of the rolls parallel to their roll axes to achieve large thickness reduction in a short time.

Reason [r]: Given

is the coefficient of friction between the rolls and the slab, and

is the angle of bite between the entrance plane and the centerline of the rolls, unaided entry of slab in the rolls can take place only if

Your answerChoose one option.

Both [a] and [r] are true, and [r] is the correct reason of [a].

Both [a] and [r] are true, but [r] is not the correct reason of [a].

Both [a] and [r] are false.

[a] is true, but [r] is false.

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Which of the following statements is/are correct?

Your answerSelect all correct options. You can choose more than one.

Ultimate analysis of coal involves determination of moisture, volatile matter, fixed carbon and ash.

Reduction of wustite in blast furnace occurs at the lower part of the stack.

Roasting involves reduction of sulfide ores to pure metals.

White metal (impure Cu

S) is produced by oxidizing Fe and S during smelting of Cu-Fe matte.

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A creep test of a pure polycrystalline metal is performed in tension and the creep strain rate is observed to decrease during the primary stage. The creep mechanism is later determined to be dislocation-climb-controlled. The observed decrease in creep strain rate is/are due to

Your answerSelect all correct options. You can choose more than one.

an increase in dislocation density.

grain growth.

a decrease in the dislocation density.

an increase in the cross-sectional area of the sample.

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Which of the following statements is/are correct for joining processes?

(A) In case of soldering and brazing, the filler material has a melting point lower than that of the metals joined.

(B) In tungsten inert gas welding, tungsten is the filler material.

(D) The following reaction is associated with thermit welding:

Note:

stands for gas.

Your answerSelect all correct options. You can choose more than one.

In case of soldering and brazing, the filler material has a melting point lower than that of the metals joined.

In tungsten inert gas welding, tungsten is the filler material.

Friction welding is a solid-state joining process.

The following reaction is associated with thermit welding:

. Note:

stands for gas.

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Which of the following statements is/are correct for non-destructive testing?

Your answerSelect all correct options. You can choose more than one.

Liquid dye penetration technique can be utilized for detecting surface cracks.

In radiographic examination, internal cracks cannot be detected.

Eddy current-based techniques can be used for detecting sub-surface defects in pure alumina at room temperature.

Ultrasonic inspection is unsuitable for inspecting sub-surface defects in high damping capacity material (e.g., cast iron).

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GATE MT topic:materials-science PYQs

Question 41

Question 42

Question 43

Question 44

Question 45

Question 46

Question 47

Question 48

Question 49

Question 50