Why are alloys preferred over pure metals in many applications?

Pure metals are generally soft, ductile, of low strength, easily corroded and hard to cast. Alloying improves these properties, so alloys are preferred:

1. Greater hardness and strength. Example: steel (Fe + C) is much harder than pure iron; Au alloyed with Cu is used in jewellery.
2. Better corrosion resistance. Example: stainless steel (Fe–Cr–Ni), bronze.
3. Lower melting point where needed. Example: solder (Sn–Pb), fuse wire.
4. Better castability and fluidity. Example: type metal.
5. Useful electrical and magnetic properties. Example: nichrome for heating coils; alnico for permanent magnets.
6. Desirable colour and appearance. Example: brass, aluminium bronze.
7. Better resistance to wear, heat and creep. Example: alloy steels for tools.