Alloy Science Essentials

Two structures explain almost every alloy:

• Substitutional alloys swap in atoms of a similar size (brass: zinc replaces some copper)
• Interstitial alloys squeeze small atoms into gaps in the lattice (steel: carbon fits between iron atoms)

The periodic table predicts which pairings work. Similar atomic radii allow substitution, while small atoms like carbon and nitrogen slip into the gaps between larger ones.