What is the difference between ferrous and non-ferrous metals and their alloys?
Ferrous metals (contain iron) and non-ferrous metals, common examples and their properties, and why alloys are used to improve a base metal.
A focused answer to AQA GCSE Engineering on ferrous and non-ferrous metals and alloys, with common examples (mild steel, cast iron, aluminium, copper, brass) and their properties and uses.
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What this dot point is asking
AQA wants you to tell ferrous metals from non-ferrous metals, give common examples with properties and uses, and explain why we alloy metals. Questions often ask you to pick a metal for a product and justify it by property, so link every metal to what it is good for.
Ferrous metals
- Mild steel: iron with up to about carbon. Tough, ductile, cheap and easy to weld, but rusts easily. Used for car bodies, nuts and bolts and structural beams.
- Cast iron: iron with a high carbon content. Very hard but brittle and strong in compression. Used for engine blocks, manhole covers and machine bases.
- High-carbon steel: iron with around to carbon. Very hard and can be heat treated, but brittle. Used for cutting tools and files.
Notice that steel is itself an alloy of iron and carbon: the amount of carbon controls how hard and how brittle the steel is, which is why low, medium and high-carbon steels behave so differently.
Non-ferrous metals
- Aluminium: light, a good conductor, corrosion resistant. Used for drinks cans, aircraft parts and window frames.
- Copper: an excellent electrical and thermal conductor, ductile. Used for wiring and pipes.
- Zinc and tin: corrosion resistant, used mainly as protective coatings (galvanising with zinc, tin plating).
Alloys
Alloying changes the metal's internal structure so the mixture outperforms the base metal for a chosen property. The reason to alloy is always to improve something specific, so a good answer names both the alloy and the property it improves.
Try this
Q1. Give one property and one use of cast iron. [2 marks]
- Cue. Hard but brittle, strong in compression; used for engine blocks or manhole covers.
Q2. Name the two metals mixed to make brass. [2 marks]
- Cue. Copper and zinc.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20183 marksExplain why an alloy such as brass is often used instead of pure copper.Show worked answer →
A good answer says what an alloy is and gives an improved property.
An alloy is a mixture of a metal with one or more other elements, made to improve the properties of the base metal. Brass is copper alloyed with zinc.
Compared with pure copper, brass is harder and stronger, more corrosion resistant and easier to machine, while keeping an attractive gold appearance. These improvements make it useful for fittings, valves and decorative items.
Markers reward defining an alloy and naming a property that the alloy improves.
AQA 20224 marksA manufacturer must choose between mild steel and aluminium for the body panels of a delivery van. Explain which properties of each metal are relevant and recommend a choice.Show worked answer →
A good answer compares named properties tied to the use, then judges.
Mild steel (ferrous) is tough, ductile and cheap and is easy to weld and press into panels, but it is dense and rusts unless protected, adding weight and maintenance.
Aluminium (non-ferrous) is much lighter and naturally corrosion resistant (it forms a protective oxide), which cuts fuel use and avoids rust, but it costs more and is harder to weld.
Recommendation: if low running cost and corrosion resistance matter most, aluminium suits the panels despite the higher material cost; if low purchase price is the priority, protected mild steel is chosen. Markers reward relevant properties for each metal and a recommendation justified by the van's needs.
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Sources & how we know this
- AQA GCSE Engineering (8852) specification — AQA (2017)