GATE MT 2020 Paper 1 — page 16

Questions 46–48 of 65. Imported answers require review unless explicitly marked reviewed.

The Mg-Sn phase diagram exhibits two eutectics on either side of the high melting intermetallic line compound, Mg

Sn, as given below.

At 561°C: L (36.9 wt.% Sn) → α (14.48 wt.% Sn) + Mg

At 203°C: L (97.87 wt.% Sn) → β-Sn (almost 100 wt.% Sn) + Mg

After the eutectic reaction has gone to completion and equilibrium has been attained at a temperature just below 561°C, the amount of eutectic constituent present in the alloy, Mg-50 wt.% Sn, is approximately ______ (in wt.%).

Given, atomic weight of Sn is 118.7 and Mg is 24.3

Your answerChoose one option.

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Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]

Assertion [a]: Low-alloy steels used for medium-temperature creep resistance often have additions of strong carbide-forming elements.

Reason [r]: During creep deformation, the particles with higher misfit with the matrix, lose coherency.

Your answerChoose one option.

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

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

Both [a] and [r] are false.

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

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Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]

Assertion [a]: The rate of homogenization in a dilute substitutional solid solution of B in A is controlled by the diffusivity of B.

Reason [r]: Atomic migration cannot occur along dislocations and grain boundaries.

Your answerChoose one option.

Both [a] and [r] are true and [r] is the correct reason for [a]

Both [a] and [r] are true but [r] is not the correct reason for [a]

Both [a] and [r] are false

[a] is true but [r] is false

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2020 · Paper 1

Question 36

Question 37

Question 38