Alloys
Alloys mix metals to improve strength or corrosion resistance.
About this topic
An alloy is a mixture of a metal with other elements, usually other metals, that has better properties than the pure metal. Pure metals are often soft because layers of identical atoms slide easily; in alloys, atoms of different sizes disrupt the regular layers, making it harder for them to slide, so alloys are harder and stronger.
Examples: steel is iron with a small amount of carbon, and stainless steel adds chromium and nickel for corrosion resistance; brass is copper and zinc; bronze is copper and tin; solder is tin and lead (or lead-free tin alloys); and duralumin is aluminium with copper, light yet strong for aircraft. Gold jewellery is alloyed because pure 24-carat gold is too soft; 18-carat gold is 75 percent gold. Alloys can also have lower melting points (solder), better conductivity, resistance to corrosion or other tailored qualities such as shape-memory in nitinol.
Making an alloy involves melting the metals together and cooling. The composition can be adjusted to give a particular strength: mild steel with about 0.2 percent carbon is tough, whereas high carbon steel with 1 percent is hard and brittle, used for tools and blades. Bridges, car bodies, coins, cutlery and surgical instruments all use alloys.
A misconception is that an alloy is a compound; it is a mixture, with components not in fixed ratios. Another is that alloys always conduct worse than pure metals, which is often but not always true.
Key ideas
- Steel is iron plus carbon
- Brass is copper plus zinc
- Different-size atoms block slipping
Quick check
Use cases: where Alloys helps
- Homework: review the key idea behind Alloys before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Alloys without notes.
- Visual learning: play with the interactive lab to see how Alloys changes when you adjust its inputs.
- Teaching a friend: explain Alloys in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Alloys?
Alloys mix metals to improve strength or corrosion resistance.
What will I learn in Alloys?
Steel is iron plus carbon. Brass is copper plus zinc. Different-size atoms block slipping.
Is Alloys part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Alloys lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Alloys?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.