Since the pig iron is hard, why is it brittle? Hard and crisp, isn't it the opposite?.
The brittle characteristics, associated with many factors such as temperature, rubber at room temperature is very soft, but at low temperature, especially fragile. Steel is the same, at room temperature, good ductility, low temperatures, and becomes glass as fragile.
A substance of great hardness, with closely arranged internal atoms, relatively close to each other, and arranged in order. On the contrary, substances of little hardness are often loosely arranged, with large spacing between atoms, and without orderly order
In order to understand, you can think about the glass, the glass is very hard, but very brittle. There are diamonds, it is the hardest material in the world, but it is very brittle, large pieces of diamonds can be easily broken
