Structure of Alloys & Their Strength
Chemistry: Cambridge International GCSE Supplement, topic 9.3.5
Structure of Alloys and Their Strength
Alloys are stronger than pure metals because different-sized atoms stop layers from sliding, giving metals hardness and strength.
What is an alloy?
- An alloy is a metal made by mixing two or more elements.
- Alloys are used widely for stronger tools.
- Pure metals have one type of atom in a regular arrangement.
- Alloys contain atoms of different sizes mixed into the metal's structure.
Atomic structure of pure metals
- Pure metals have atoms arranged in layers.
- These layers slide over each other easily.
- Sliding layers make pure metals soft and easy to shape.
- For example, pure copper is soft because its layers move smoothly.
Atomic structure of alloys
- Alloys have different-sized atoms mixed into the metal layers.
- Larger and smaller atoms distort the regular arrangement.
- Distorted layers cannot slide easily over each other.
- This restriction makes alloys harder and stronger than pure metals.
Why are alloys stronger?
- Different-sized atoms block the movement of metal layers.
- This blocking increases the metal's resistance to bending.
- Alloys do not bend or deform as easily as pure metals.
- For example, steel (an iron and carbon alloy) is much harder than pure iron.
Summary of alloy strength
- Metals are harder and stronger when atoms vary in size.
- This variation stops layers from sliding in the structure.
- Alloys offer practical uses due to their improved strength.
Test yourself on Structure of Alloys & Their Strength
What is an alloy defined as?
Which statement is true regarding the properties and examples of alloys?