MAE 200 Test 1 Review 2

In the left hand side figure below, the Miller indices of direction are a. [011] b. [101] c. [110]

101

. In the figure below of atomic potential with distance between ions, identify the solid with higher melting point. Give the figure assigned (A or B)

B

11. In the figure above, identify the solid with shortest equilibrium distance between the ions.

B

In the left hand figure below (choose the origin) the Miller indices of the plane ABCD are a. (101) b. (1-10) c. (-101)

a. (101)

The number of lattice sites or atoms per cubic centimeter in Iron are a. 0.085x1024 b. 0.042x1024 c. 0.17x1024

a. 0.085x1024

Iron crystallizes in a body-centered-cubic (bcc) lattice with a lattice constant a0 of 0.287nm, and has an atomic weight of 55.85 g/mole. The atomic radius for iron (in nm) is a. 0.124 nm b. 0.287 nm c. 0.201

a. 0.124 nm

The number of vacancies in Iron per cubic centimeter at 720oC are a. 0.2x1015 b. 0.1x1015 c. 0.4x1020

a. 0.2x1015

The radius of the atom in terms of lattice parameter, a , in the right hand side arrangement in the figure below is a. 0.433 a b. 0.354 a c. 0.5 a

a. 0.433 a

Activation energy for diffusion of carbon is a. 0.444 eV/K b. -0.444eV/K c. 1.100 eV/K

a. 0.444 eV/K

The mass of each iron atom is a. 55.85/(6.03x10^23) gms b. 55.85x(6.03x10^23) gms c. (6.03x10^23)/55.85 gms

a. 55.85/(6.03x10^23) gms

The density of iron is a. 7.87 gms/cm3 b. 3.33 gms/cm3 c. 10.74 gms/cm3

a. 7.87 gms/cm3

In the right hand side figure below, the Miller indices of direction are a. [11-1] b. [1-11] c. [-111]

a. [11-1]

Close packed hexagonal structures like graphite with large c/a ratio are a. anisotropic b. isotropic c. both a and b

a. anisotropic

Diffusion of nickel atoms in copper with fcc structure takes place along a. face diagonals b. body diagonals c. along the cube edge

a. face diagonals

The lubricating properties of graphite are a result of a. high c/a ratio b. low c/a ratio c. fcc structure of graphite

a. high c/a ratio

Diffusion of carbon in iron takes place via a. interstitial mechanism b. vacancy mechanism c. both a and b

a. interstitial mechanism

Of the two structures shown below, the structure that gold atoms take up is a. left hand side b. right hand side c. neither

a. left hand side

The depth of the carburized layer after high temperature carburization for 1 hr at 600oC is 2 micrometers in steel. If the same process is done but for 2hrs at 700 oC the depth of the carburized layer is 4 micrometers. The average distance travelled by an atom in carburization is given by a. one-dimensional diffusion b. two-dimensional diffusion c. three-dimensional diffusion

a. one-dimensional diffusion

Orientation of the Burgers vector of an edge dislocation to the sense vector is a. perpendicular b. parallel c. both a and b

a. perpendicular

The activation energy for diffusion of carbon in iron compared to that of diffusion of nickel in iron will be a. smaller b. higher c. same

a. smaller

In the right hand side figure below (choose the origin) , the Miller indices of the plane ABC are a. (-111) b. (1-11) c. (11-1)

b. (1-11)

The concentration of hydrogen atoms inside a vessel is kept at 1021 atoms/cm3. The vessel has a palladium foil of area 2 cm2 and the thickness of the foil is 1 micrometer. If the diffusion coefficient of hydrogen in palladium is 10-6 cm2/sec, the hydrogen atom concentration outside the foil is maintained at zero. Concentration gradient of the hydrogen across the palladium foil is a. 1019 atoms/cm2 b. -1025 atoms/cm4 c. -1023 atoms/cm4

b. -1025 atoms/cm4

The radius of the atom in terms of lattice parameter, a , in the left hand side arrangement in the figure below is a. 0.433 a b. 0.354 a c. 0.5 a

b. 0.354 a

Diffusion coefficient of carbon at 600 oC and 700 oC, respectively in steel are a. 1.11x10-8 and 0.56x10-8 cm2/sec b. 0.56x10-11 and 1.1x10-11 cm2/sec c. 1.1x1011 and 0.56x1011 cm2/sec

b. 0.56x10-11 and 1.1x10-11 cm2/sec

Flux of atoms across the palladium foil is a. 1019 atoms/cm2.sec into the vessel b. 1019 atoms/cm2 .sec out of the vessel c. 1017 atoms/cm2 out of the vessel

b. 1019 atoms/cm2 .sec out of the vessel

Assuming a vacancy formation energy of 1.7 eV per vacancy, the ratio of vacant sites to lattice sites in Iron at 720oC is a. 2.37x10-8 b. 2.37x10-9 c. 2.37x10-4

b. 2.37x10-9

Rate of supply of atoms outside the vessel is a. 1017 atoms/sec b. 2x1019 atoms/sec c. 2x1017 atoms/cm2.sec

b. 2x1019 atoms/sec

The shortest distance between atoms in a face-centered cubic (fcc) crystal is in the direction: a. <100> b. <110> c. <111> d. <210>

b. <110>

The conservation of energy is given by a. Fick's second law b. Fick's first law c. diffusion equation d. gradient of concentration

b. Fick's first law

A combination of vacancy and interstitial of a cation is called a. intersititial point defect b. Frenkel defect c. Schottky defect cation and anion d. none of the above

b. Frenkel defect

Diffusion of smaller atoms in a lattice compared to that of larger atoms is expected to be a. slower b. faster c. same

b. faster

The structure that is close packed is a. simple cubic b. fcc and hcp c. bcc and simple cubic d. all the above

b. fcc and hcp

The ABABAB stacking sequence is present in a. face-centered cubic b. hexagonal close packed c. simple cubic d. all of the above contain close packed planes

b. hexagonal close packed

For favorable use of a material for structural applications, it is important for the material to possess a. high strength b. high strength and ability to deform c. high ductility

b. high strength and ability to deform

Ceramic materials without impurities in general are electrically a. conductors b. insulators c. both a and b

b. insulators

A pentagonal unit cell is not permitted because a. it does not satisfy the rotational symmetry b. it does not satisfy the translational symmetry and leaves holes in the solid c. both a and b

b. it does not satisfy the translational symmetry and leaves holes in the solid

The ability to deform of polymers arises from the a. weak covalent bond within the chain b. the weak van der Walls bond between the chains c. the strong covalent bond between the chains

b. the weak van der Walls bond between the chains

The diffusion of nickel in iron takes place by a. interstitial mechanism b. vacancy mechanism c. both a and b

b. vacancy mechanism

. The number of grains observed in a microscope in 1 sq. inch at a magnification of 100X is 64. The ASTM grain size index is a. 7 b. 13 c. 8

c. 8

The number of atoms that touch an atom in the center of a body-centered cubic (bcc) structure? a. 4 b. 6 c. 8 d. 12

c. 8

Successful jump of an atom to the next position depends on a. overcoming the activation barrier b. probability of finding a vacant site c. both a and b simultaneously

c. both a and b simultaneously

Permanent deformation occurs by a. vacancy diffusion b. interstitial diffusion c. motion of dislocations d. migration of grain boundaries

c. motion of dislocations

A grain boundary is an example of a a. point defect b. line defect c. surface defect d. none of the above

c. surface defect

Structures are classified into crystal systems according to a. density b. bonding c. coordination number d. symmetry

d. symmetry