32 Unit Cell

The smallest group of particles in the material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive pattern of the unit cell along its principal axes.

In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. Cubic crystal system is referrred to as body-centered cubic (bcc) space lattice. This is one of the most common and simplest shapes found in crystals and minerals.

There are three main varieties of these crystals:

• Primitive cubic (abbreviated cP and alternatively called simple cubic)
• Body-centered cubic (abbreviated cI or bcc)
• Face-centered cubic (abbreviated cF or fcc)

We will focus on bcc and fcc as we build our background knowledge to how heat affects the microstructure of steel.

The crystal structure and symmetry play a critical role in determining many physical properties, which will be discussed later in this book.

In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.

Derived from Crystal structure – Wikipedia and Cubic crystal system – Wikipedia accessed and available online, 8 February 2024.