MAE 20
Winter 2011
Assignment 2
Due Tues., Jan. 18 at the beginning of class
Finish reading Chapter 3 , begin reading Chapter 4 (in Callister, 8th edition)
Work problems (Callister 8th edition):
3.23
3.31
3.40
3.42
3.53
3.54
3.66
4.3
4.7
MAE 20
Exam #2(a) Solutions
Problem 1
A tensile test is performed on a metal specimen, and it is found that a true plastic strain of 0.20
is produced when a true stress of 575 MPa is applied; for the same metal, the value of the strain
hardening coefficie
MAE 20
Exam #2(b) solutions
Problem 1
For an 18-8 Mo stainless steel (see figure), predict
the time to rupture for a component that is subjected
to a stress of 110 MPa at 500C.
! = 110 MPa
T = 500C = 773 K
(
)
From plot , T 20 + log tR = 22 " 103 K # hr
(
MAE 20
Exam #2(c) solutions
Problem 1
A 4 mm diameter cylindrical rod fabricated
from a 2014-T6 aluminum alloy (see figure) is
subjected to reversed tension-compression
load cycling along its axis. If the maximum
tensile and compressive loads are +2500 N
American University of Beirut
MECH 340-Engineering Materials
Spring 2013- Dr. Mohamad Nassereddine
Name:
ID:
Problem 1. Structures-15 pts
a. Figure 1 is a micrograph of an alloy at a magnification of 200. Find the ASTM
grain size. Count grains on the edge
Problem 1
Nitrogen from a gaseous phase is to
be diffused into pure iron. If the
surface concentration is maintained
at 0.2 wt.% N, what will be the
concentration at 0.3 mm from the
surface after 5 hours? The diffusion
coefficient for N in Fe is 2.5 x 10-
Problem 1
Rhodium has an atomic radius of 0.1345 nm, a density of 12.41 gm/cm3 and atomic weight, ARh
= 102.91 gm/mole. Determine if the structure is BCC or FCC.
Problem 2
An alloy contains 20 wt.% zinc and 80 wt.% copper. What is the concentration of Zn
Problem 1
An alloy contains 10 wt.% zinc and 90 wt.% copper. What is the concentration of Zn (in atoms
of Zn/m3) in the alloy?
DATA: ACu = 63.55 gm/mole, AZn = 65.41 gm/mole, Cu = 8.94 gm/cm3, Zn = 7.13 gm/cm3
Problem 2
Nitrogen from a gaseous phase is
to
Chapter 5: Diffusion in Solids
ISSUES TO ADDRESS.
How does diffusion occur?
Why is it an important part of processing?
How can the rate of diffusion be predicted for
some simple cases?
How does diffusion depend on structure
and temperature?
Chapter 5
CHAPTER 4:
IMPERFECTIONS IN SOLIDS
ISSUES TO ADDRESS.
What are the solidification mechanisms?
What types of defects arise in solids?
Can the number and type of defects be varied
and controlled?
How do defects affect material properties?
Are defects u
Chapter 3: The Structure of Crystalline Solids
ISSUES TO ADDRESS.
How do atoms assemble into solid structures?
(for now, focus on metals)
How does the density of a material depend on
its structure?
When do material properties vary with the
sample (i.e.
Line Defects
Dislocations:
are line defects,
slip between crystal planes result when dislocations move,
produce permanent (plastic) deformation.
Schematic of Zinc (HCP):
before deformation
after tensile elongation
slip steps
Adapted from Fig. 7.8, Ca
MECH340-
SPRING2012-
AUB-
MIDTERM 1
AUB-SPRING 2012- MECH 340- MIDTERM I
STUDENT NAME:
For instructor use only:
Problem 1:
Problem 2:
Problem 3:
Final Grade:
ID:
MECH340-
SPRING2012-
AUB-
MIDTERM 1
Part I - Crystalline structures-18 pts Total
a) On
MAE 20
Example Midterm 1
Closed book and notes
All questions worth 10 points
1.
A BCC iron metal foil is 25 m thick. Assume that all of the unit cells are arranged so
that ao is perpendicular to the foil surface. For a 1 cm x 1 cm piece of foil, calc ulat
MAE 20
Winter 2011
Assignment 5
Due Tues. Feb. 22 at the beginning of class
Finish reading Chapter 6, begin reading Chapter 8 (in Callister, 8th edition)
Work problems (Callister 8th edition):
6.7
6.22
6.29
6.41
6.44
8.3
8.7
8.13
8.18
MAE 20
Winter 2011
Assignment 4
7.6 (a) Compare planar densities (Section 3.11 and Problem 3.54) for the (100), (110), and (111) planes
for FCC.
(b) Compare planar densities (Problem 3.55) for the (100), (110), and (111) planes for BCC.
Solution
(a) For t
MAE 20
Winter 2011
Assignment 6
Due Tues. March 1 at the beginning of class
Finish reading Chapter 8, begin reading Chapter 9 (in Callister, 8th edition)
Work problems (Callister 8th edition):
8.3
8.7
8.13
8.18
8.22
8.27
8.34
8.D6
MAE 20
Winter 2011
Assignment 5
6.7 For a bronze alloy, the stress at which plastic deformation begins is 275 MPa (40,000 psi), and the
modulus of elasticity is 115 GPa (16.7 106 psi).
(a) What is the maximum load that may be applied to a specimen with a
MAE 20
Winter 2011
Assignment 3 solutions
4.3 Calculate the activation energy for vacancy formation in aluminum, given that the equilibrium
number of vacancies at 500 C (773 K) is 7.57 1023 m-3. The atomic weight and density (at 500 C) for
aluminum are, r
MAE 20
Winter 2011
Assignment 6
8.3 If the specific surface energy for soda-lime glass is 0.30 J/m2, using data contained in Table 12.5,
compute the critical stress required for the propagation of a surface crack of length 0.05 mm.
Solution
We may determi
MAE 20
Winter 2011
Assignment 2 solutions
3.23 List the point coordinates of the titanium, barium, and oxygen ions for a unit cell of the perovskite
crystal structure (Figure 12.6).
Solution
In Figure 12.6, the barium ions are situated at all corner posit
AUB-Spring 2013
MECH340: (Quiz II-1H15)
Problem 1. 30 pts One kilogram of an alloy of 60 weight % Pb and 40 weight % Sn is
slowly cooled from 300o C. Refer to the lead-tin phase diagram of the Figure 1 and
calculate the following:
a) The weight percent of