Mechanical properties of Solids

Outline:  Brittle materials break suddenly without deforming plastically.

Explanation: If you apply force to a brittle material, it won’t deform plastically, but will suddenly snap when the force is big enough.

Brittle materials can also be quite weak if they have cracks in them.

Examples: Ceramics (glass and pottery)

Outline:  Ductile materials can be drawn out into wires without losing their strength.

Explanation: You can change the shape of ductile materials by drawing them into wires or other shapes. It is key to remember that they keep their strength when they are deformed like this.

Examples: Copper

Outline:  Malleable materials change shape but may lose their strength.

Explanation: The shape of malleable materials can be changed fairly easily, e.g hammering. The difference between malleable and ductile materials is that malleable materials won’t necessarily keep their strength.

Examples: Gold, Brass

Outline:  Hard materials are very resistant to cutting, indentation and abrasion.

Explanation: The structure of hard materials means they are resistant to cutting indentation (denting) and abrasion (scratching).

Examples: Hardened steel, Diamond

Outline:  Stiff materials have a high resistance to bending and stretching.

Explanation: Changing the shape of stiff materials is very difficult as they are resistant to both bending and stretching. Stiffness is measured by the Young modulus – the higher the value, the stiffer the material.

Examples: Hard hats and Safety boots

Outline:  Tough materials are really difficult to break.

Explanation: Toughness is a measure of the energy a material can absorb before it breaks. Really tough materials can absorb a lot of energy so are very difficult to break. They plastically deform prior to fracture.

Examples: Polythene, Kevlar