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WorksheetsCrystal Imperfection
Total questions: 22
Worksheet time: 28mins
Following is not the 2-dimensional imperfection
Twin boundary
Dislocation
Surface
Grain boundary
Thermodynamically stable defects
Point defects
Line defects
Surface defects
Volume defects
Conservative movement of dislocations
Slip
Climb
Both slip and climb
None
Burger’s vector changes with
Kind of dislocation
Length of dislocation
Both kind and length of dislocation
None
Which of the following is false?
Line defects are thermodynamically stable
Dislocation can end inside a crystal without forming loop
ABC ABC ABC…is stacking sequence for HCP crystal
All
Which of the following having higher strength?
coarse grain pearlite structure
fine grain pearlite structure
A defect where atoms occupy the empty space between existing atoms within a crystal
substitutional
interstitial
Dislocation has less influence to material properties.
correct
incorrect
Cations are present in the interstitial sites in __________.
Frenkel defect
Schottky defect
Schottky defect is observed in crystals when __________.
some cations move from their lattice site to interstitial sites.
the equal number of cations and anions are missing from the lattice
In which of the following arrangements octahedral voids are formed?
SC
BCC
FCC
HCP
If 30 grains are observed in 2 square inch area at 400 magnification. Then ASTM grain size number of the structure is
6.9
7.9
8.9
none of these
2.24 * 10^(-25)
1.46*10^(-8)
2.27*10^(-5)
2.7*10^(-4)
0.5a
1.732a
1.414a
0.7a
Smallest Strain energy per unit dislocation length in FCC crystal is............. Where G=shear modulus, a= lattice parameter
0.5Ga^2
0.25Ga^2
Ga^2
0.353Ga^2
Cross slip motion occurs in
edge dislocation
screw dislocation
mixed dislocation
all of the above
Which of the following is/are straight line dislocation(s)?
edge
screw
mixed
Which of the following is produced by a series of edge dislocation?
tilt boundary
grain boundary
stacking fault
twin boundary
Presence of defects
increases configuration entropy
decreases configuration entropy
Etchant is used to
clearly visualise the grain boundaries
polish the surface
magnify the grains
Parmanent/plastic deformation occurs
by slip motion of dislocation
twining
Both
Stacking fault is common in
BCC
SC
FCC
HCP
