C1 Alloys

Pure metals often aren't quite right for certain jobs, so scientists mix two metals together (or mix metal with a non-metal) - creating an alloy with the properties they want

Pure iron tends to be a bit too bendy

• Iron straight from the balst furnace is only 96% iron. The other 4% is impurities such as carbon

• This impure iron is used as cast iron. It's handy for making ornamental railings, but it doesn't have many other uses because it's brittle

• So all the impurities are removed from most of the blast furnace iron. This pure iron has a regular arrangement of identical atoms. The layers of atoms can slide over each other, which makes the iron soft and easily shaped. This iron is far too bendy for most uses

Most iron is converted into steel - an alloy

Moat of the pure iron is changed into alloys called steels. Steels are formed by adding small amounts of carbon and sometimes other metals to the iron

Low carbon steel (0.1% carbon)

• Easily shaped
• Used to make car bodies

High carbon steel (1.5% carbon)

• Very hard and inflexible
• Used to make blades for cutting tools and bridges

Stainless steel (chromium added, and sometimes nickel)

• Corrosion-resistant
• Used to make cutlery and containers for corrosive substances

Alloys are harder than pure metals

• Different elements have different sized atoms
• When an element such as carbon is added to pure iron, the smaller carbon atom will upset the layers of pure iron atoms
• This makes it more difficult for them to slide over each other
• Therefore a harder material is created
  

Many metals in use today are actually alloys

Bronze = Copper + Tin

• Bronze is harder than copper
• It's good for making medals and statues

Cupronickel = Copper + Nickel

• This is hard and corrosion resistant
• It's used to make 'silver' coins

Gold alloys

• Pure gold is very soft
• Metals such as zinc, copper, silver, palladium and nickel are used to harden the gold
• The resultant alloys are used to make jewellery

Aluminium alloys

• Aluminum has a low density
• To make it stronger, it's alloyed with small amounts of other metals
• These alloys are then used to make aircraft