18
Electronic Materials
181 A current of 10 A is passed through a 1-mm-diameter wire 1000 m long. Calculate
the power loss if the wire is made of (a) aluminum, (b) silicon, and (c) silicon carbide. (See Table 181).
Solution:
Power I 2R I 2/sA 110 A2 2 110
20
Photonic Materials
2010 A beam of photons strikes a material at an angle of 25 to the normal of the surface.
Which, if any, of the materials listed in Table 201 could cause the beam of photons
to continue at an angle of 18 to 20 from the normal of the
19
Magnetic Materials
196 Calculate and compare the maximum magnetization we would expect in iron,
nickel, cobalt, and gadolinium. There are seven electrons in the 4f level of
gadolinium.
Solution:
Iron: The number of atoms/m3 is:
2 atoms/cell
0.085 1030
17
Construction Materials
171 A sample of wood with dimensions 3 in. 4 in. 12 in. has a dry density of 0.35
g/cm3. (a) Calculate the number of gallons of water that must be absorbed by the
sample to contain 120% water. (b) Calculate the density after the
16
Composites: Teamwork and
Synergy in Materials
167 Nickel containing 2 wt% thorium is produced in powder form, consolidated into a
part, and sintered in the presence of oxygen, causing all of the thorium to produce
ThO2 spheres 80 nm in diameter. Calcul
15
Polymers
156(a)
Suppose that 20 g of benzoyl peroxide are introduced to 5 kg of propylene monomer
(see Table 153). If 30% of the initiator groups are effective, calculate the expected
degree of polymerization and the molecular weight of the polypropyle
11
Dispersion Strengthening by Phase
Transformations and Heat Treatment
112
Determine the constants c and n in Equation 112 that describe the rate of crystallization of polypropylene at 140C. (See Figure 1131)
Solution:
f 1 exp1ct n 2
T 140C 413 K
We can
14
Ceramic Materials
1442 The specific gravity of Al2O3 is 3.96 g/cm3. A ceramic part is produced by sintering
alumina powder. It weighs 80 g when dry, 92 g after it has soaked in water, and 58 g
when suspended in water. Calculate the apparent porosity, t
13
Nonferrous Alloys
131 In some cases, we may be more interested in cost per unit volume than in cost per
unit weight. Rework Table 131 to show the cost in terms of $/cm3. Does this
change/alter the relationship between the different materials?
Solution:
12
Ferrous Alloys
124 Calculate the amounts of ferrite, cementite, primary microconstituent, and pearlite in
the following steels: (a) 1015, (b) 1035, (c) 1095, and (d) 10130.
Solution: (a) 1015:
a
primary a
6.67 0.15
100 97.8%
6.67 0
Fe3C 2.2%
0.77 0.1
10
Dispersion Strengthening and
Eutectic Phase Diagrams
1022 A hypothetical phase diagram is shown in Figure 1032. (a) Are any intermetallic
compounds present? If so, identify them and determine whether they are stoichiometric or nonstoichiometric. (b) Id
8
Principles of Solidification
810
Suppose that liquid nickel is undercooled until homogeneous nucleation occurs.
Calculate (a) the critical radius of the nucleus required, and (b) the number of nickel
atoms in the nucleus. Assume that the lattice paramet
9
Solid Solutions and Phase Equilibrium
915 The unary phase diagram for SiO2 is shown in Figure 93(c). Locate the triple point
where solid, liquid, and vapor coexist and give the temperature and the type of solid
present. What do the other triple points i
5
Atom and Ion Movements in Materials
512
Atoms are found to move from one lattice position to another at the rate of 5 105
jumps/s at 400oC when the activation energy for their movement is 30,000 cal/mol.
Calculate the jump rate at 750oC.
Solution:
Rate
6
Mechanical Properties and Behavior
624
A 850-lb force is applied to a 0.15-in. diameter nickel wire having a yield strength
of 45,000 psi and a tensile strength of 55,000 psi. Determine (a) whether the wire
will plastically deform and (b) whether the wi
7
Strain Hardening and Annealing
75
A 0.505-in.-diameter metal bar with a 2-in. gage length l0 is subjected to a tensile
test. The following measurements are made in the plastic region:
Change in
Gage length (in.)
0.2103
0.4428
0.6997
Force (lb)
27,500
27
4
Imperfections in the Atomic and Ionic Arrangements
41 Calculate the number of vacancies per cm3 expected in copper at 1080oC (just below the melting temperature). The activation energy for vacancy formation is 20,000 cal/mol. Solution: n = (4 atoms/u.c.
3
Atomic and Ionic Arrangements
325 Calculate the atomic radius in cm for the following: (a) BCC metal with ao = 0.3294 nm and one atom per lattice point; and (b) FCC metal with ao = 4.0862 and one atom per lattice point. Solution: (a) For BCC metals, r =
2
Atomic Structure
26(a) Aluminum foil used for storing food weighs about 0.3 g per square inch. How many atoms of aluminum are contained in this sample of foil? Solution: In a one square inch sample: number = (0.3 g)(6.02 1023 atoms/mol) = 6.69 1021 atom
1
Introduction to Materials Science and Engineering
15 Iron is often coated with a thin layer of zinc if it is to be used outside. What characteristics do you think the zinc provides to this coated, or galvanized, steel? What precautions should be conside
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DECANATO DE ESTUDIOS PROFESIONALES
PLAN DE ESTUDIOS DE
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VIGENCIA : SEPTIEMBRE 2013
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Matemticas IV
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SOLUTIONS TO PROBLEMS PREFACE This section of instructors materials contains solutions and answers to all problems and questions that appear in the textbook. My penmanship leaves something to be desired; therefore, I generated these solutions/answers usin