Assignment 1

Due Date: 30/10/2011

Problem 1(a) Aluminium foil used for storing food weighs about 0.3 g per square inch. How many

atoms of aluminium are contained in one cubic inch of this material?

Density of Aluminium = 11.36 g/cm3

Atomic Weight of Aluminium = 26.981 g/molAvogadro’s Number = 6.023 x 1023 atoms/mol

(b) Calculate and compare the number of atoms per cubic centimeter in (a) lead and (b) lithium.

Density of Lead = 11.36 g/cm3

Density of Lithium = 0.534 g/cm3

Atomic Weight of Lead = 207.19 g/molAtomic Weight of Lithium = 6.94 g/mol

Problem 2Calculate the atomic radius in cm for the following: (a) BCC metal with ao 0.3294 nm and one atom per lattice point; and (b) FCC metal with ao 4.0862 Å and one atom per lattice point.

Problem 3Determine the crystal structure for the following: (a) a metal with ao 4.9489 Å, r 1.75 Å and one atom per lattice point; and (b) a metal with ao 0.42906 nm, r 0.1858 nm and one atom per lattice point.

Problem 4The density of thorium, which has the FCC structure and one atom per lattice point, is 11.72 g/cm3. The atomic weight of thorium is 232 g/mol. Calculate the following: (a) the lattice parameter and (b) the atomic radius of thorium

Problem 5The diffusion coefficient for Cr3 in Cr2O3 is 6 x1015 cm2/s at 727 oC and is 1 x 109 cm2/s at 1400 oC. Calculate the following:(a) the activation energy and (b) the constant Do

Problem 6A carburizing process is carried out on a 0.10% C steel by introducing 1.0% C at the surface at 980 oC, where the iron is FCC. Calculate the following:(a) the carbon content at 0.01 cm, 0.05 cm, and 0.10 cm beneath the surface after 1 h(b) Plot the results (%C vs distance, x) and comment on them

Do = 0.23 m2/s, Activation Energy (Q) = 23,000 cal/mol, R (gas constant) = 1.987 cal/mol.k