summary

Many engineers will be inclined to think first of
1. Mechanical strength
2. Ductility
3. Impact resistance
Include such behavior under extremes of temperature or other external conditions.

Properties also includes
1. Electrical and thermal conductivity
2. Optical properties
3. Corrosion resistance
4. The ability of the material to be fabricated into complex shapes and to be decorated or coated for appearance

Classes of materials
-metals
-ceramics (and glasses, which are usually made up of the same elements but with a different atomic arrangement)
-polymers (or ’plastics’ to use the more common name)
-composites (which combine several materials to achieve unique or economical combinations of properties) e.g. wood, concrete

Metal
-opaque to light
-reflective
-ductile
-electrically and thermal conducting

Ceramics and glasses
-brittle
-can be transparent to light
-good insulators
Particularly useful at high temperatures or in corrosive environment

Polymers (most)
-cannot withstand high temperatures
-insulators
-highly deformable
Some
-have unique elastic properties (rubber bands)
-semiconductors

Choice of materials
-strength and hardness
-ductility
-fracture mode, fracture, creep
-environmental consideration, corrosion
-easy of fabrication