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Final Exam with Answers - Materials Science | EGR 221, Exams of Materials science

Material Type: Exam; Professor: Lulay; Class: Materials Science; Subject: Engineering; University: University of Portland; Term: Fall 2007;

Typology: Exams

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University of Portland
EGR 221 - Materials Science
Exam 2 (CLOSED BOOK, CLOSED NOTES)
November 2, 2007, Dr. Ken Lulay
Name
1) {15 pts} Answer true (T) or false (F):
T F The process of recovery in a metal has little or no effect on grain size.
T F Slip systems are composted of a slip direction and slip plane – these are the
directions and planes within a crystal which have the lowest atomic linear
density and planar density, respectively.
T F Equilibrium solid phases are stable (lowest free energy) and will not change
phase even if they are heated sufficiently to cause them to completely melt.
T F Resolved shear stress is a material property.
T F Hardness and tensile strength are directly related. In other words, if you
increase the tensile strength of a material you also increase the hardness.
2) {20 pts} Fill in the blanks with the correct terminology:
a) When a material is plastically deformed it may become stronger and harder. This is
referred to as .
b) is a type of fracture for which significant plastic
deformation occurs.
c) A homogeneous portion of a system that has uniform physical and chemical
characteristics is called a:
d) The time dependent strain that can occur in materials at elevated temperatures is
referred to as .
e) The material property that characterizes a material’s ability to withstand deformation
by surface indentation or abrasion is:
3) Use the copper-nickel phase diagram below (next page) to answer the following
questions. For FULL CREDIT, make marks on the diagram to communicate what
you are doing. SHOW all of your work! Unless otherwise stated, the alloy is 60wt%
nickel (Ni) and 40wt% copper (Cu) at 1320°C
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University of Portland EGR 221 - Materials Science Exam 2 (CLOSED BOOK, CLOSED NOTES) November 2, 2007, Dr. Ken Lulay

Name 1) {15 pts} Answer true (T) or false (F):

T F The process of recovery in a metal has little or no effect on grain size.

T F Slip systems are composted of a slip direction and slip plane – these are the directions and planes within a crystal which have the lowest atomic linear density and planar density, respectively.

T F Equilibrium solid phases are stable (lowest free energy) and will not change phase even if they are heated sufficiently to cause them to completely melt.

T F Resolved shear stress is a material property.

T F Hardness and tensile strength are directly related. In other words, if you increase the tensile strength of a material you also increase the hardness.

2) {20 pts} Fill in the blanks with the correct terminology:

a) When a material is plastically deformed it may become stronger and harder. This is

referred to as.

b) is a type of fracture for which significant plastic

deformation occurs.

c) A homogeneous portion of a system that has uniform physical and chemical

characteristics is called a:

d) The time dependent strain that can occur in materials at elevated temperatures is

referred to as.

e) The material property that characterizes a material’s ability to withstand deformation

by surface indentation or abrasion is:

3) Use the copper-nickel phase diagram below (next page) to answer the following questions. For FULL CREDIT, make marks on the diagram to communicate what you are doing. SHOW all of your work! Unless otherwise stated, the alloy is 60wt% nickel (Ni) and 40wt% copper (Cu) at 1320°C

(for detailed information, see the problem statement for Problem 3 on previous page).

a) {10 pts} How much of each phase is present?

b) {10 pts} What is the composition of the phases present?

c) {3 pts} What critical but basic assumption is necessary to answer the above questions regarding reading a phase diagram?

d) {7 pts} If the alloy was to be quickly cooled from liquid to solid, a non-homogeneous (inhomogeneous) microstructure would form. What is this called and briefly describe why it occurs.

e) {5 pts} Briefly describe one negative effect of the inhomogeneous microstructure discussed in part (d).