Metallurgical Engineering
GATE MT topic:dislocation-theory PYQs
Build your understanding with focused practice from past exam papers.
Questions 11–18 of 18. Imported answers require independent review unless marked reviewed.
Question 40
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Find the correct match between dislocation reactions (Column A) to the descriptions (Column B)
Column A
(P)
(Q)
(R)
Column B
(1) Leading partials merging to form a Lomer-Cottrell lock in an FCC metal
(2) Energetically unfavorable dislocation reaction in an FCC metal
(3) Typical dislocation reaction in a BCC metal
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Two dislocation lines parallel to z-axis lying in the x-z plane are shown in the figure. The glide force (in Newton) exerted by the edge dislocation on the screw dislocation is: __________ (round off to nearest integer).
For the edge, the shear stress component is given by:
Given: Shear modulus, G = 28 GPa
Poisson’s ratio, ν = 0.3
Burgers vector, b = 0.29 nm
Distance between the two dislocations = 0.5 nmLog in to check the answer
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In the edge dislocation configuration given in the figure, dislocations X and Y are fixed and separated by a distance
on the same slip plane. Dislocation Z is free to glide on a parallel slip plane. The two slip planes are separated by a distance
. Which one of the following statements is TRUE regarding the stability of dislocation Z at positions 1, 2 and 3?Assume all dislocations have identical Burgers vector.
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Which one of the following dislocation reactions is NOT feasible in a FCC crystal?
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Cold working of iron leads to increase in dislocation density from
to
. The associated stored energy (in
, rounded off to one decimal place) is ________.Given: Shear modulus of iron = 82 GPa, Burger’s vector,
,
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Consider a dilute substitutional solid solution of X in a metal A. The powder diffraction pattern of this alloy reveals that all the peaks have shifted to the left when compared to those for pure A (with no split of peaks). If such a solute interacts and segregates to an edge dislocation, which of the following positions around the dislocation will it preferentially occupy?
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Stress required to operate a Frank-Read source of length L is approximately given by:
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At low temperature, two parallel edge dislocations lying on parallel slip planes are shown in different configurations below.
Match the following:
Configuration [P]
Configuration [Q]
Configuration [R]
Configuration [S]
[1] Dislocations repel
[2] Dislocations attract
[3] Dislocations are in stable equilibrium
[4] Dislocations are in unstable equilibrium
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