Material Science and Metallurgy

2

Atomic Bonding and Crystal Structure

2.1 INTRODUCTION

The properties of any material are highly dependent on the type of bond between the atoms and the arrangement of atoms in the unit cell of a lattice in the crystal. Most of the solid materials are either crystalline (e.g. copper, aluminium, zinc and iron) or non-crystalline, i.e. amorphous (e.g. glasses, plastics and wood) in nature. Graphite is soft and greasy, while diamond is the hardest material, even though both are made of carbon atoms. The change in the behaviour of same carbon atom in graphite and diamond is directly attributed to the type of interatomic bonding.

Many mechanical properties such as strength, ductility and hardness depend upon the geometry of the crystal, i.e. how ...