Alloys

📚 Key Concepts

🔹 Real-Life Example

Pure gold is too soft for jewelry – it would bend and scratch easily. So jewelers mix gold with copper or silver to make it harder. The resulting alloy (like 18k gold) is stronger while retaining gold’s beauty. Similarly, pure iron is soft, but steel (iron + carbon) is strong enough for skyscrapers!

Alloy: A homogeneous mixture of two or more metals, or a metal with a non-metal, prepared by mixing the components in molten state.

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🧪 Why Make Alloys?

🔸 Advantages Over Pure Metals

  1. Increased Strength: Steel vs iron
  2. Corrosion Resistance: Stainless steel vs iron
  3. Better Properties: Bronze vs copper
  4. Cost Reduction: Mixing expensive metal with cheaper one

🔍 Important Alloys

🔸 Steel Alloys

  • Mild Steel: Iron + 0.2% Carbon (car bodies, nails)
  • Medium Steel: Iron + 0.6% Carbon (machinery)
  • High Carbon Steel: Iron + 1.5% Carbon (cutting tools)
  • Stainless Steel: Iron + Chromium + Nickel (utensils, medical instruments)

🔸 Copper Alloys

  • Bronze: Copper + Tin (statues, medals, bearings)
  • Brass: Copper + Zinc (musical instruments, decorative items)

🔸 Other Important Alloys

  • Duralumin: Aluminum + Copper + Magnesium + Manganese (aircraft bodies)
  • Solder: Lead + Tin (joining electrical wires)
  • Amalgam: Mercury + other metals (dental fillings)
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