Alloys are compounds made up of more than one metal. Often, non-metal elements are introduced into the mix to add certain characteristics. Discover more about what it takes to create these miracle metals.
Throughout history, humans have tried to make things a little better. Add this, add that and hopefully something even better will be formed. By sheer luck and experimentation, people have created alloyed metals that have made their lives better.
Here are some common alloys:
- Steel = iron (metal) + carbon (non-metal)
- Bronze = copper (metal) + tin (metal)
- Brass = copper (metal) + zinc (metal)
Pure metals often have useful properties, like conductivity, strength and resistance. However, metal alloys combine these properties to create a metal that is even better than its components. It’s the sum of its parts that makes it stronger.
Steel is iron with most of the impurities removed (like silica, phosphorus and sulphur), giving it the advantage of greatly improved strength.
An open-hearth furnace can be used to create steel from pig iron. Of course, this is a rough guide, so do not attempt to create your own steel.
- Place pig iron, limestone and iron ore into an open-hearth furnace.
- Heat the furnace to about 871°C.
- The limestone and ore will form a slag that floats on the surface.
- Impurities, including carbon, will be oxidised and float out of the iron into the slag.
- When the carbon content is right, you have carbon steel.
The development of steel requires finding the right combination of carbon and iron (99% iron and 1% carbon) to produce a metal that is stronger, lighter and more malleable than pure iron.
Around 2000 BCE, a new metal swept through Europe. Bronze was popular because it could be sharpened, moulded, and even be melted down into other objects. Its hardness meant it was great for making tools and weapons too.
This is how ancient metallurgists create bronze – an alloy so important they named the era after it. Again, do not try this at home.
- First, collect the metals tin and copper.
- Heat the metals and mix them together.
- As the two metals melt, they will combine to form liquid bronze.
- Pour the liquid into clay or sand moulds and allow to cool.
This method was called casting, and it was used to make most bronze objects – from swords and knives, to brooches and pins.
Brass is a metal made up of copper and zinc. This alloy is stronger and harder than copper, but not as strong or hard as steel.
Ancient metalworkers in Syria and Turkey created bronze as early as 3000 B.C. They sometimes made brass without knowing it. This is because tin and zinc ore deposits are sometimes found together, and the two materials have similar colours and properties.
- Gather copper and zinc.
- Combine the raw materials into a molten metal.
- The copper alloy scrap is weighed and transferred into a furnace where it is melted at about 1,050°C.
- Place the liquid into a mould and allow it to solidify.
Brass is easy to form into various shapes, conducts heat, and is resistant to corrosion. Because of these properties, brass is used to make pipes and tubes, weather-stripping and other architectural trim pieces, screws, radiators, musical instruments and more.
The art of combining molten metals, or mixing metals with non-metals, has produced amazing results. Once again, these “recipes” are a general guide, for educational purposes only and should not be attempted at home.