MSE 702
Quiz 1
1. Local Burgers vector is defined in
a. FS/RH convention
b. SF/RH convention
ID Number:
c. both a and b
(b
)
2. A dislocation loop with Burgers vector always oriented perpendicular to the sense vector is
a. glide loop
b. prismatic loop
c.
MSE 702
Test 1
Class Part
ID:
1. Two edge dislocations with parallel sense vectors and perpendicular Burgers vectors
are present in a crystal. If only glide of the dislocations is allowed, determine the relative
positions where the dislocations will come
MSE 702
Class Part 2
ID:
1.
(a) List four methods that can be used to determine the vacancy concentration in metals.
(b) Derive an expression for the concentration of defects using Siedman-Ballufi experiments.
(c) In aluminum, the difference between the b
Test 1
MSE 702-601
ID Number:
Class Part of test. This is close book. All the necessary equations are provided on the last page
of this test. Time: 2 to 3 hours.
Q1. Consider a screw dislocation situated along the z-axis at the origin. An edge dislocation
Test 2
MSE 702
ID Number:
Q1.
(a) Given the thin film solution in the form
C(x,t) = cfw_M/(4Dt)1/2 exp(-x2/4Dt)
Show that the mean square distance travelled by an atom in three dimensional diffusion is 6Dt
where D is the diffusion coefficient, M is the m
MSE 702
Test 2
Class part
ID number:
To be completed in the class time 1 hr, close book.
Q1.
(a) Give the general definition of flux including diffusion and drift terms.
(b) Assume the interaction of a dislocation with dopant atoms to be of the form
E(r,)
MSE 702
Quiz 1
ID No:
1. The spirals observed on the crystal grown from aqueous solutions were showing
evidence of dislocations emerging at the surface that are
a. edge dislocations
b. screw dislocations
c. neither a nor b
( b)
2. The large width of the X
Test 1 MSE 702 Class Part
ID :
Solutions to all these questions in the class part and take home part are available in the resources
section- in previous exams or assignments sections.
Time is 90 minutes.
Equations given at the end of the examination may b
MSE 701
Test 1
ID Number:
Class Part A
1. A straight edge dislocation and a glide circular dislocation loop with the same Burgers
vector are lying in the same plane. Show that the circular dislocation loop can not remain
circular. Neglect lattice friction
Test 1
MSE 702
ID:
Take Home Part of the examination. Open book examination. Consulting books or notes
or any other source is allowed. If you have any questions, send them to the instructor on
the message board.
Q1. Represent a slip band by an array of di
MSE 702 Quiz 5
ID. No:
1. Ficks law is satisfied in many materials because
a. energy gradients are present
b. defects responsible for diffusion are in equilibrium
c. conservation of mass is fundamental
( b)
2. In the correlated motion of an atom by vacanc
Test 1
MSE 702
Class Part
ID :
1. Show that there is no interaction between a screw dislocation and an edge dislocation whose
sense vector is parallel to that of the screw dislocation.
2. An edge dislocation of length L pinned at the end points climbs in
MSE 702
Test 3 Class part
ID:
-5
Time : 2.5 hours, closed book. K=8.6x10 eV/K
Q1.
(a) Derive an expression for the concentration of V-, V- - , V+, and V+ in terms of neutral
vacancy concentrations and show which of these defects are prevalent in n-type an
Q1.a. Show that the mean square distance traveled by an atom in one-dimensional
diffusion is 2Dt where D is the diffusion coefficient and t is the time of diffusion. Use the
thin film solution in the form ,
C(x,t) =cfw_M/(4Dt)1/2 expcfw_-x2/4Dt and
x2C(x,
Test 1
MSE 702
ID No:
1. a. The L-shaped dislocation is present with the applied stress as shown on the
crystal. Determine the force acting on the two segments of the L-shaped
dislocation. The Burgers vector of the dislocation is perpendicular to both the
MSE 702
Quiz #3
ID Number:
1. Drift term in the diffusion equation is characterized by term proportional to
a. concentration gradient
b. concentration
c. both a and b
(b )
2. In a crystal with uniform concentration to start with, the term that is importan
MSE 702
Quiz 2
ID No:
1. The diffusion term in the expression for flux is proportional to
a. concentration
b. concentration gradient
c. kT
(b )
2. Concentration dependence of diffusion coefficient arises because
a. chemical potential energy is a function
MSE 702
1.
a.
b.
c.
Quiz 4
ID No:
Vacancies are equilibrium defects because
the free energy of formation of a vacancy is negative
the free energy of formation of vacancy is positive
the entropy of mixing is positive
( c)
2.
The reason defects are associat
Quiz 1
MSE 702
Feb 2, 2006
1. Burgers circuit taken enclosing two oppositely signed dislocations will give
a. no net closure vector
b. sum of the magnitudes of the two Burgers vectors as
closure vector c. nonzero closure vector if the dislocations are end
MSE 702 Quiz #1
ID Number:
1. Drift term in the diffusion equation is characterized by term proportional to
a. concentration gradient
b. concentration
c. both a and b
(b
)
2. In a crystal with uniform concentration to start with, the term that is importan
MSE 702
Quiz #3
ID#
1. In the experiments of Ballufi and Seidman, the themal strain less lattice strain in aluminum is
expressed in the form exp(2.4) exp(-0.76/kT). Thus, the enthalpy of formation of
a. interstitials is 2.4 eV b. vacancies is 0.76 eV
c. v
Test 2
MSE 702
ID No:
Test 2 consists of 2 parts. Part 1 is class part and part 2 is Take Home that need to be
submitted by April 12 class time. Each part carries 50 points.
Part 1. Answer both questions. Time 1hr :15 minutes
Question 1.
(a) Using the thi
Test 1
MSE 702
ID:
Formulae provided in the additional page may be used.
1. (a) Derive an expression for the Osmotic force acting on a dislocation with sense
vector and Burgers vector b in a crystal with excess vacancy concentration.
Increase in the vacan
Q1.a. Show that the mean square distance traveled by an atom in one-dimensional
diffusion is 2Dt where D is the diffusion coefficient and t is the time of diffusion. Use the
thin film solution in the form ,
C(x,t) =cfw_M/(4Dt)1/2 expcfw_-x2/4Dt and
x2C(x,