Brittleness, a mechanical property of metals, is the property of a metals to bend or deform without breaking or shattering the metal.
The opposite of this is ductility which is the ability to deform without breaking or shattering the metal, while a brittle metal would break or crack without a change of shape. Examples of Brittle metals are:

- Cast Iron
- Cast Aluminum
- Very Hard Steel
- etc.
Brittle metals are not suitable for heavy loads, as it could break easily and can cause damages.