Metals and alloys
- Explain how the addition of small quantities of other elements can increase the hardness of steel.
- Describe the principal feature that allows a mineral deposit to be classed as an ore.
1. To make any alloy, you mix one metal with another element (metallic or not) to get a new substance with particular properties. In steel, you mix Iron and Carbon. The large Iron atoms require a certain amount of space between them and this leaves gaps between the atoms. These gaps account for the softness of Iron. When you heat Iron in the presence of Carbon, Carbon atoms fill in the gaps between the Iron atoms. This makes the metal harder and thus steel is formed. The concentration of Carbon atoms affects the hardness of the steel. More carbon atoms means the gaps are filled more completely by 2 or more Carbon atoms and thus the steel becomes more rigid. Fewer carbon atoms and only 1 Carbon atom will sit in each gap making the steel softer.