Final Examination, December 2016 MSE 2191H1F – Structure...

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UNIVERSITY OF TORONTO FACULTY OF APPLIED SCIENCE AND ENGINEERING

Final Examination, December 2016

MSE 2191H1F – Structure and Characterization of

Materials Exam Type: A

Examiner: D.D. Perovic

Answer all questions on these pages.

Individual questions are NOT of equal value.

Marks for each question are indicated.

Approved calculators only.

Note: Multiple choice questions are worth 2 marks each.

1(a) Substitutional solid solution solubility is promoted in alloys:

a) with difference in atomic radii greater than ~ 15% b) large grain size c) small difference in electronegativity of elements d) all of the above

1(b) Analysis of helium content of a material can be performed using the following

technique: a) Energy-dispersive x-ray microanalysis (EDX) b) Auger electron spectroscopy (AES) c) Atomic force microscopy (AFM) d) X-ray photoelectron spectroscopy (XPS)

1(c) The angle between the Burgers vector and line direction of a mixed dislocation is:

a) 0˚ b) 45˚ c) 90˚ d) none of the above


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1(d) The spacing between two spots in an electron diffraction pattern is: a) proportional to the camera length of the microscope b) proportional to the lattice plane spacing c) are represented by a g-vector in real space d) all of the above

1(e) The x-ray reflections from a mostly amorphous sample are: a) moderately well-defined b) very sharp c) poorly defined or absent d) totally absent

1(f) The pole of a great circle on a stereographic projection: a) corresponds to the projection of all plane normals at a given angle to the pole b) is determined from the angle between two plane normals c) is the projection of the axis of the zone of planes whose normals lie on the great

circle d) is determined from the reverse manipulation of (c)

1(g) Analysis of hydrogen content of a material can be performed using the following

technique: e) Energy-dispersive x-ray analysis (EDX) f) Auger electron spectroscopy (AES) g) Electron energy-loss spectroscopy (EELS) h) X-ray photoelectron spectroscopy (XPS)

1(h) A structure of low-angle twist grain boundaries can be described in terms of:

a) edge dislocations b) screw dislocations c) mixed dislocations d) twin boundaries

1(i) FTIR spectroscopy measures bond vibration frequencies of materials where:

a) frequency decreases with increasing atomic weight b) frequency increases with increasing bond energy c) frequency is proportional to wavenumber d) all of the above are true

1(j) An L2,3 edge would be observed on a spectrum using the following technique:

a) Energy-dispersive x-ray analysis (EDX) b) Auger electron spectroscopy (AES) c) Electron energy-loss spectroscopy (EELS) d) X-ray photoelectron spectroscopy (XPS).


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2(a) The diffraction pattern shown below was acquired using x-rays with λ = 0.1541 nm from

a pure polycrystalline material with cubic crystal structure. Solve the diffraction pattern and index the reflections. (8 marks)

2(b) Is the Bravais lattice of the material FCC or BCC? (4 marks)

2(c) Determine the lattice parameter of the material. (4 marks)


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2(d) Using the stereographic projection below, indicate the following planes on the diagram: (i) 100, (ii) 110, (iii) 111 (iv) 010. (4 marks)

3(a) Consider the following single crystal:

Ni (100) p (2×2) – S (Ni = fcc, a = 0.352 nm) Sketch the atomic surface structure and select a characterization technique of your choice

that could be used to determine the chemical composition of the adsorbate. (7 marks) 3(b) Explain why the region of a specimen sampled by SEM using BSE imaging and EDX

microanalysis is always greater than the incident electron beam irradiated area. (6 marks) 3(c) Explain the difference between energy-dispersive x-ray spectroscopy (EDX) and Auger

electron spectroscopy (AES) in terms of electronic transitions. Why is not possible to do AES in a conventional SEM? (7 marks)


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4(a) Using a dislocation description explain why single crystals of Fe are ductile and NaCl crystals are brittle. (4 marks)

4(b) A simple cubic metal has a lattice parameter of 0.25 nm. A [100] tilt boundary is formed with a misorientation angle of 2.5˚. Compute the dislocation spacing in the boundary. (4 marks)

4(c) Sketch the transmission electron diffraction patterns you would expect to see for the

following structures of the same material: (a) amorphous (b) nanocrystalline (c) textured polycrystalline and (d) single crystalline. (8 marks)

4(d) Consider a material that has grain boundaries of two types, (i) low-angle tilt boundaries

and (ii) Σ-3 CSL tilt boundaries. Differentiate the structural models used to describe each type of grain boundary. (4 marks)


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5. You have been hired as a Materials Engineer by a large company, which manufactures Ti-6Al-4V hip implants as shown below. An implant fractured in a patient after 5 years in service. On your first day of work you are given some characterization problems to solve based on the experimental techniques discussed in this course [i.e. optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX), electron energy-loss spectroscopy (EELS) x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning probe microscopy (SPM), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and secondary-ion mass spectrometry (SIMS)].

(a) Describe how you would determine if the two-phase Ti-alloy microstructure of the femoral stem alloy conformed to manufacturer’s specifications. (4 marks)


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(b) How would you determine if the molecular weight of the polyethylene insert degraded over time while in service? (4 marks)

(c) How would you determine the mode of fracture of the femoral stem? (4 marks) (d) A region of the femoral stem has a 1 nm ceramic coating of calcium phosphate designed

to enhance bone bonding? How would you quantitatively determine the composition of the coating. (4 marks)

(e) How would you determine if the ceramic coating on the femoral head was crystalline or

amorphous in structure? (4 marks)


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Useful Equations and Constants:

( )2 2 22 21 1 h k ld a

= + + ( )2 2 22 2 21 1 1h k ld a c

= + + 2 2 22 2 2 21 1 1 1h k ld a b c

= + +

2 sindλ θ= sin(θ / 2) = b / 2d 2 ( )

1

n n n

Ni hu kv lw

hkl nF f e π + +=∑

3 5

2 4 6

11

i i i

i i i

e e ee e e

π π π

π π π

= = = −

= = = +

( 1) ,

,

n i n

n i n i

e where n is any in teger

e e where n is any in teger

π

π π−

= −

=

hp mvλ

= = 2hmeV

λ = 0 2

eVm mc

= +

1/ 2

0 20

2 12

h

eVm eVm c

=⎡ ⎤⎛ ⎞

+⎢ ⎥⎜ ⎟⎝ ⎠⎣ ⎦

λ ( )0.50.5 6

1.226

1 0.9788 10nm

V Vλ

−=

+ ×

Rd Lλ= [ ] ( ) 0UVW hkl hU kV lW= + + =g ( )2 1.67

0.89

2.76 10KO

AVR mZ

µρ

−×=

E hν= hcEλ

= swlhcV

λ = ( )22 2

1 113.6f i

E Z in eVn n⎛ ⎞

Δ ≈ − × −⎜ ⎟⎜ ⎟⎝ ⎠

( )KE h BEν φ= − + A B CKE E E E φ≈ − − − 212

KE mv=

c = 2.998x108 m/s e = 1.602x10-19 C m0 =9.11x10-31 kg

h = 6.626x10-34 J·s h = 4.136x10-15 eV·s 1 eV = 1.602x10-19 J

Condition for FCC diffraction: h,k,l are unmixed

Condition for BCC diffraction: h + k + l = even

Final Examination, December 2016 MSE 2191H1F – Structure...

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