APL102 July 2014 Minor I
APL102: Materials Science and Engineering
Minor Test I 28th. Aug. 2014 Maximum Marks 60
1
Why do we not have an end-centred tetragonal lattice? Consider both the cases of end centring: (a) centring of opposite square faces of the unit cell and (b) centring of opposite rectangular faces of the unit cell.
12
2
Draw a plane in a BCC unit cell . Show your choice of origin and axes. Include in your drawing all the close packed directions lying in this plane and give their Miller indices. You should specify a positive sense on your direction with help of an arrow and make your Miller indices consistent with that direction.
12
3
First three peaks in a powder x-ray diffraction pattern from a cubic crystal appears at Bragg angle =13.63, 22.63 and 26.82 when CuK radiation with a wavelength of 1.54 Å is used. Determine the structure and lattice parameter of the material.
12
4
Iron changes from a low temperature BCC phase to a high temperature FCC phase upon heating above 910C. Determine the % increase or decrease in the volume of an iron sample undergoing this transformation assuming that the radius of the iron atoms do not change during the transformation.
5
(a)
The following quote is from G.E. Dieter, Mechanical Metallurgy, 3rd. Edn., p104
“The most elementary crystal structure is the simple cubic lattice. This is the type of structure cell found for ionic crystals, such as NaCl and LiF, but not for any of the metals.”
Your comments?
(b)
Discuss the changes in structure (with help of sketches) and properties obtained on addition of soda to fused silica glass
(c)
Consider a stacking of close packed layers of atoms in a repeating sequence described by
Select a unit cell in this structure by choosing the origin at the centre of an atom and x and y directions parallel to two close-packed directions with =120; and the z-axis normal to the x-y plane. Choose a=b=2R (here R is the radius of the atom) and c as the distance between
Minor Test I 28th. Aug. 2014 Maximum Marks 60
1
Why do we not have an end-centred tetragonal lattice? Consider both the cases of end centring: (a) centring of opposite square faces of the unit cell and (b) centring of opposite rectangular faces of the unit cell.
12
2
Draw a plane in a BCC unit cell . Show your choice of origin and axes. Include in your drawing all the close packed directions lying in this plane and give their Miller indices. You should specify a positive sense on your direction with help of an arrow and make your Miller indices consistent with that direction.
12
3
First three peaks in a powder x-ray diffraction pattern from a cubic crystal appears at Bragg angle =13.63, 22.63 and 26.82 when CuK radiation with a wavelength of 1.54 Å is used. Determine the structure and lattice parameter of the material.
12
4
Iron changes from a low temperature BCC phase to a high temperature FCC phase upon heating above 910C. Determine the % increase or decrease in the volume of an iron sample undergoing this transformation assuming that the radius of the iron atoms do not change during the transformation.
5
(a)
The following quote is from G.E. Dieter, Mechanical Metallurgy, 3rd. Edn., p104
“The most elementary crystal structure is the simple cubic lattice. This is the type of structure cell found for ionic crystals, such as NaCl and LiF, but not for any of the metals.”
Your comments?
(b)
Discuss the changes in structure (with help of sketches) and properties obtained on addition of soda to fused silica glass
(c)
Consider a stacking of close packed layers of atoms in a repeating sequence described by
Select a unit cell in this structure by choosing the origin at the centre of an atom and x and y directions parallel to two close-packed directions with =120; and the z-axis normal to the x-y plane. Choose a=b=2R (here R is the radius of the atom) and c as the distance between