University at Buffalo
State University of New York
Department of Mechanical and Aerospace Engineering
MAE 381
Nov. 18, 2013
Test No. 5 solution
Close book.
No calculator allowed. Time allowed: 40 minutes only.
This test consists of 5 problems on 2 pages.
State University of New York, University at Buffalo
Department of Mechanical and Aerospace Engineering
MAE 381 Engineering Materials
Professor Deborah Chung
Dec. 13, 2012
Final Examination Solution, Closed Book, 3 hours.
The examination consists of 4 prob
MAE381 Exam #1
NAME: Last 4 digits of Person Number:_ _
Calculator allowed. Close book. no cell phones. Time: 90 minutes-
All problems are worth 6 points unless otherwise noted.
1] Complete the following chart: lead1 box is 1/2 point, 6 points total]
Elem
9.2 At 100C, what is the maximum solubility of the following:
(a) Pb in Sn
(b) Sn in Pb
Solution
(a) From Figure 9.8, the maximum solubility of Pb in Sn at 100C corresponds to the position of the (
+ ) phase boundary at this temperature, or to about 2 wt%
Chapter 2
113
2.4 Indium has two naturally occurring isotopes:
In with an atomic weight of 112.904 amu, and
115
In with an
atomic weight of 114.904 amu. If the average atomic weight for In is 114.818 amu, calculate the fraction-ofoccurrences of these two
CHAPTER 4
IMPERFECTIONS IN SOLIDS
PROBLEM SOLUTIONS
4.4 Calculate the number of vacancies per cubic meter in gold (Au) at 900C. The energy for vacancy formation is
0.98 eV/atom. Furthermore, the density and atomic weight for Au are 18.63 g/cm 3 (at 900C)
MAE381 Summer 2014 Exam #2 Review
1) If copper (Cu) at 900C (1173K) has 3.2 x 1023 vacancies per cubic meter, what is the energy for
vacancy formation, in eV? Cu has an atomic weight of 63.55 g/mol and a density of 8.6 g/cm3 at
900C.
2) Compute the radius
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MAE381 Summer 2015 Exam #2
:5
NAME: r L TH)sz Last 4 digits of Person Number:
1) Consider a piece of copper (Cu) at 900°C (1173K). How many copper atoms are there if the
volume is 1 cm]? if the energy for vacancy formation is 1.26 eV, how many vacancies a
CHAPTER 11
APPLICATIONS AND PROCESSING OF METAL ALLOYS
PROBLEM SOLUTIONS
11.19 In your own words describe the following heat-treatment procedures for steels and, for each, the intended
final microstructure:
(a) full annealing
(b) normalizing
(c) quenching
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_ MAE381 Summer 2015 Exam 3
NAME: Last 4 digits of Person Number-.
Calculator & Ruler allowed. Close book, no cell phones
1) The following is the Iron-iron Carbide phase diagram:
~: 11i.:«-|";
r':'-:.'.=pr
Te':'pe-a'ure \
ELCC
Pam
Temperat
MAE381 Exam 3 Review
From Chapter 9 you should be able to:
Understand and interpret phase diagrams (See In Class Assignment 3 for review) including:
3. Identify phases and microconstituents
b Calculate compositions and mass fractions
c. Sketch microstruct
MAE381 Summer 2014 Exam #2 Review Solutions
1) If copper (Cu) at 900C (1173K) has 3.2 x 1023 vacancies per cubic meter, what is the energy for
vacancy formation, in eV? Cu has an atomic weight of 63.55 g/mol and a density of 8.6 g/cm3 at
900C.
= 8.6
3
1
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0.01
0.001
20 0 20 40 60 30 100 120
Temperature PC}
Fig u r e 9 .2
Pressuretemperature phase diagram for H20. Intersection of the
dashed horizontal line at 1 arm pressure with the solici-quuici phase
bo
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O
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MAE381 Fall 2015 Exam #2
\.
NAME: K‘: 4‘ Last 4 digits of Person Number:—
1) Consider a piece of copper (Cu) at 900°C (1173K). How many copper atoms are there if the
volume is 1 cma? If the energy of vacancy formation is 1.26 eV, how many vacancies are th
MAE381 Fall 2015 Exam #3
NAME: .k 3-; 3 H11 hells Last 4 digits of Person Number:_ _ _ _
1) Consider the following Stress — Strain curve for some unknown metal: (15 points)
I s
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6; ._ _
a. IOU I
“s
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a
g I
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MAE381 Exam #4
NAME: KEY
Last 4 digits of Person Number:_ _ _ _
1) Identify and explain 2 strengthening mechanisms for metals. (20 points)
Grain Size Reduction: Misalignment of crystal orientations requires dislocation to change
direction and the atomic d
8.4 An MgO component must not fail when a tensile stress of 13.5 MPa (1960 psi) is applied. Determine the
maximum allowable surface crack length if the surface energy of MgO is 1.0 J/m 2. Data found in Table 12.5 may
prove helpful.
Solution
The maximum al
CHAPTER 17
CORROSION AND DEGRADATION OF MATERIALS
PROBLEM SOLUTIONS
Electrochemical Considerations
17.1 (a) Briefly explain the difference between oxidation and reduction electrochemical reactions.
(b) Which reaction occurs at the anode and which at the c
10.15 (a) Briefly describe the phenomena of superheating and supercooling.
(b) Why do these phenomena occur?
Answer
(a) Superheating and supercooling correspond, respectively, to heating or cooling above or below a phase
transition temperature without the
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Sum amass 25cm MPC,
Realm) AC 7 G96, 1 T
4 = IZS'OO MPG
O
GUT LfldD STMSS Fm ALUMNUA LS ~3§MPm
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