What is the Difference Between Substitutional and Interstitial Alloys?

The main difference between substitutional and interstitial alloys lies in how they form and the size of the atoms involved:

• Substitutional Alloys:
• Form when one metal atom substitutes another metal atom in the crystal lattice.
• Involve relatively similar-sized atoms.
• Examples include brass (copper and zinc) and bronze (copper and tin).
• Interstitial Alloys:
• Form when small atoms fit into gaps between larger atoms in the crystal lattice.
• Involve different-sized atoms, with at least a 15% difference in size.
• An example is steel (iron and carbon).

Due to their differences in formation and atomic sizes, substitutional and interstitial alloys have distinct properties:

• Substitutional alloys tend to be malleable and ductile.
• Interstitial alloys are usually less malleable and ductile, but harder, more corrosion-resistant, and have a higher melting point.

Comparative Table: Substitutional vs Interstitial Alloys

The main difference between substitutional and interstitial alloys lies in how they form. Here is a table comparing the two types of alloys:

Substitutional alloys are created when atoms of one element replace atoms of another element in the crystal lattice, typically when the atoms have similar sizes. On the other hand, interstitial alloys form when smaller atoms fit into the interstitial spaces (holes) in the lattice structure of larger atoms.