Mixing changes metals

The idea

The properties of any metal change when it is mixed with another substance, metal or non-metal, so alloying is a very good method of getting desired properties.

Soft iron

Pure iron is very soft and stretches easily when hot. Yet iron is the most widely used metal.

How can iron be made hard and strong?

• By mixing it with a small amount of carbon
• By beating it thinner
• By keeping it in water

Change the iron

Press Next step.

Mix to improve

Adding another substance changes the properties of a metal. It can be a metal or a non-metal. Pure iron is very soft, but with a little carbon it is hard and strong, and with nickel and chromium it becomes stainless steel. Alloying is a very good way of getting the properties we want.

The properties of any metal change when it is mixed with another substance, metal or non-metal, so alloying is a very good method of getting desired properties.

Notes

Mixing a metal with another substance, a metal or a non-metal, changes its properties; alloying is a very good way to get desired properties.

Check yourself

Pure iron is ...

Iron mixed with a small amount of carbon becomes ...

Stainless steel is made by mixing iron with ...

In an example, 2000 kg of an iron mixture contains about 0.05 % carbon. About how many kilograms of carbon is that?

Answer: 1 kg

0.05 % of 2000 kg = 2000 × 0.05 ÷ 100 = 1 kg.

• hard and does not rust. That describes stainless steel, which is iron mixed with nickel and chromium.
• harder than steel. Mixing iron with a small amount of carbon makes it hard and strong; pure iron is very soft.
• very soft and stretches easily when hot — correct. Yes!
• hard and strong — correct. Yes!
• softer. Pure iron is very soft; adding carbon makes it hard and strong.
• a gas. The mixture is still a solid metal; it becomes hard and strong.
• sulphur and sodium. The book names nickel and chromium for stainless steel.
• nickel and chromium — correct. Yes!
• zinc and tin. The book names nickel and chromium for stainless steel.