rr411812 x ray metallography

Code No: RR411812 Set No. 1

IV B.Tech I Semester Regular Examinations, November 2007X-RAY METALLOGRAPHY

(Metallurgy & Material Technology)Time: 3 hours Max Marks: 80

Answer any FIVE QuestionsAll Questions carry equal marks

1. Discuss the history of X-radiations. Describe the methods for X-ray production.[16]

2. Derive simplified expressions for F2 for the Wurtzite form of ZnS, including therules governing observed reflections. This crystal is hexagonal and contains 2 ZnSper unit cell, located in the following positions: [16]

Zn : 0 0 0 1/3 2/3 1/2S : 0 0 3/8 1/3 2/3 7/8

3. Explain the following:

(a) Measurement of X-ray intensity [6]

(b) Stereographic projection [5]

(c) Resolving power of a Camera. [5]

4. (a) How does Debye-Scherrer diffraction pattern look? [4]

(b) Where is Debye-Scherrer method useful? [6]

(c) Explain how a powder camera is superior to a Diffractometer with examples.[6]

5. (a) Explain the working of Back reflection Cameras. [7]

(b) For a Debye pattern made in a 4.63 Cm diameter Camera with CuK radia-tion. Calculate the separation of the components of the K doublet in degreesand in Centimeters for = 50, 300, 550 and 800 . [9]

6. Write notes on the following:

(a) Crystal quality [6]

(b) Particle size [5]

(c) Grain size. [5]

7. With an example discuss the structure determination in detail. [16]

8. A uniaxial Tensile stress of 100 Ksi is being measured in Iron by reflecting X-raysfrom (211) planes at = 0 and 450. Take the lattice parameter a of the stressfree Iron to be 2.8665A0, E = 30X106 Psi and v = 0.29.Calculate d0, dn and di to five significant figures. [16]

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1. (a) Explain with a neat sketch, the order of reflection. [7]

(b) The atomic radius of Molybdenum atom is 0.1363 nm. Compute the inter-atomic spacing for (111) set of planes in the molybdenum crystal. The crystalstructure of molybdenum is bcc. What is the interplanar spacing for (220) setof planes? [9]

2. (a) For BCC Iron, compute (i) the interplanar spacing (ii) the diffracting angle forthe (220) set of planes. The lattice parameter of Iron is 0.2889 nm. Assumethat a monochromatic radiation having a wavelength of 0.1541 nm is used andthe order of reflection is done.

(b) (i) Calculate the interplanar spacing for (110) and (221) sets of planes inAluminum (ii) When a monochromatic X-ray beam of X-rays of wavelength0.1542 nm is used, the first order reflection from (113) set of planes occurs at . What is the value of ? [8+8]

3. Write short notes on the following:

(a) Multiplicity factor

(b) Lorentz factor. [8+8]

4. (a) Describe how powder photograph is taken?

(b) Describe how powder pattern of Cubic crystals can be analyzed. [8+8]

5. Given a square piece of X-ray film 10 Cm X 10 Cm radiation of =0.152 nm andpowdered NaCl with a lattice parameter 0.563 nm, devise a diffraction experimentin such a fashion that the rays from (111) planes produce a circle of diameter 0.1m.

[16]

6. What is the principle involved in Diffractometre method (The texture of Sheet).With neat sketch explain the working of Diffractometre method. [16]

7. What is the basic principle involved in crystal structure determination? Explainvarious steps involved in determination of unknown structures. [16]

8. Compare and Contrast Coherent and Incoherent radiation. [16]

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1. (a) What is the frequency (per second) and energy per quantum (in joules) ofx-ray beams of wavelength 0.71A0 (Mo K ) and 1.54A0 (Cu K )? [7]

(b) Calculate the velocity and kinetic energy with which the electrons strike thetarget of an X-ray tube operating at a voltage V. Determine the short-wavelength limit of the continuous spectrum emitted and the maximum energyper quantum of radiation? [9]

2. (a) Mention various defects that occur in Crystal. Write in brief on each of them.

(b) Nickel shows the diffraction maximum at 2 = 101.5020 . The wavelength ofX-rays is equal to 1.541A0 . Calculate the lattice parameter of Nickel cell ifthe above reflection corresponds to (310) plane (n =1). [8+8]

3. (a) Explain in detail the scattering of X-rays by an atom. [7]

(b) What is structure factor? Derive an expression for the structure factor. Cal-culate the structure factor for NaCl. [9]

4. (a) How do you distinguish between BCC and FCC structures from powder pat-tern.

(b) Write a note on Rotating crystal method. [8+8]

5. What is the principle involved in X-ray spectrometer? With neat sketch, Explainthe construction and working of X-ray spectrometer. [16]

6. Write notes on the following:

(a) Crystal quality [6]

(b) Particle size [5]

(c) Grain size. [5]

7. If the same (hkl) reflection from a given material is examined in a diffractometrewith successively different wavelengths, how does the penetration depth x varywith ? Explain. (Assume the Wavelengths used lie on the same branch of theabsorption curve of the material). [16]


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1. With a neat sketch, describing the parts of X-ray tube, design a method for X-rayproduction. [16]

2. (a) Write a note on Diffraction Directions.

(b) Derive an expression for the absorption factor of a diffractiometer specimen inthe form of a flat plate of finite thickness t. (Note that the absorption factornow depends on ). [8+8]

3. What are the experimental methods of X-ray diffraction? Explain each of them inbrief. [16]

4. Debye Scherrer pattern of Molybdinum (BCC) is made with Cu K radiation. Thefirst four lines on this pattern were observed to have the following values. [16]

Line 1 30.30

2 19.20

3 46.70

4 53.60

Index these lines and calculate their relative integrated intensities.

5. (a) What are back reflection Focussing Cameras? What is the principle involvedin it? Draw a neat sketch.

(b) Explain the reasons for Background radiation in Powder Camera method.[8+8]

6. A Transmission Laue photograph is made of an Aluminum crystal with a crystalto film distance of 5 Cm. When viewed from the X-ray source, the Laue spots havethe following x, y coordinates, measured (in Inches) from the center to the film. [16]

X Y+1.39 +1.10+0.89 -1.62+1.02 -0.95-1.95 +0.80-0.21 -0.58

Plot these spots on a sheet of graph paper. By means of a Greninger chart, de-termine the orientation of the crystal, plot all poles of the form {100}, {110} and

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{111} , and give the coordinates of the {100} poles in terms of latitude and longi-tude measured from the center of the projection.

7. Explain the following:

(a) Chemical analysis by parameter measurement [5]

(b) Techniques used in stress measurement [5]

(c) What are the errors that can be occurred and how they are classified in theprecise parameter measurements? [6]


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rr411812 x ray metallography

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