Crystal Structure, direction and planes (Excluding Miller indices)

Question 1

What are the four types of Unit Cells?

Answer 1

Simple (SC)
Body Centred (BCC)
Base Centred
Face Centred (FCC)

Question 2

What is the equation for the Atomic Packing Factor?

Answer 2

APF = Volume of atoms in unit cell / Volume of unit cell

APF = (atoms per unit cell)*(volume per atom)/(volume of unit cell)

Question 3

Which type of unit cell has the highest APF?

Answer 3

FCC - 0.74

BCC - 0.68
(SC - 0.52)

Question 4

What is the equation for the Theoretical density?

Answer 4

Density = Mass of atoms in unit cell/ Total Volume of Unit Cell

p = nA/VcNa

Question 5

Where does slip occur?

Answer 5

Slip occurs on planes that have the greatest density of atoms, and along directions with the highest density. (Along the closest packed directions on the closest packed planes)

Question 6

What is the equation for the Linear density?

Answer 6

LD = number of atoms centred on a direction vector/ Length of direction vector

Question 7

What is the equation for Planar Density?

Answer 7

PD = Number of atoms centred on a plane/ Area of plane