Question

A-What is the trend of atomic size in the periodic table and why?

B-Determine the bonding type of given atoms (Fe-Fe, Ca-Cl, O-O, H-H)

C-Calculate the density of Al, given its atomic radius and crystal structure.

D-Calculate the atomic packing factor for FCC and BCC structures

E-Compute the elongation due to thermal expansion of given material.

F-Given the vacancy concentration, calculate E_v^f

G-How can edge dislocation move? Draw illustrations.

H-Why are vacancies important to dislocation motions?

I-What is the mechanism for plasticity deformation?

G-What is the effect of grain size on mechanical properties?

K-How does diffusion occur in metals and how does diffusivity change with temperature and why?

L-Compute the stress and strain of a cable for given loading condition; compute the cross-sectional area change

M-Given a stress-strain curve, determine Young’s modulus, the yield strength, the ultimate strength, and the fracture strength.

N-Strengthening mechanisms

Answer 1

A. ans.

The atomic size decreases gradually from left to right in the periodic table.

The electrons are added to the same energy level the nucleus is increases.The nuclear charg attracts the electrons more strongly it results atomic size decreases.

From top to bottom the atomic size increases due to the number of electrons increases.

B. Ans.

Fe-Fe - Metallic bond : Formed by the positively charged metallic atoms.

Ca-Cl Ionic bond : They forms ions by the transfer of electrons.

O-O Covalent bond : By the sharing of electrons

H-H : By the sharing of electrons

C.Ans.

Density = Mass/ volume

=2.7 g/cm³

Radius =143ppm

Alluminium have FCC structure.

D.Ans.

APF = No. of particles in unit * Volume of each particle / Volume occupied by unit

For FCC

Unit cell contains 6 *1/2 + 8 * 1/8 = 4 atoms

FCC APF = (4 * 4/3 π(√2 a /4)³)/a³

⁼π√2/6

^=0.74

For BCC

APF = 2 *4/3πr³ / (4r/√3)³

⁼ π√3 /8 =0.68