Alloys and their properties
Vocabulary
| English | Chinese | Pinyin |
|---|---|---|
| alloy | 合金 | hé jīn |
| steel | 钢 | gāng |
| brass | 黄铜 | huáng tóng |
| bronze | 青铜 | qīng tóng |
| stainless steel | 不锈钢 | bù xiù gāng |
Mixing metals for strength
- Pure metals are often too soft or weak for the job.
- Mixing them makes alloys 合金 — usually stronger and more useful than the pure metal.
Explore
Alloy property lab
See why mixing atoms changes metal properties.
Practice
An alloy is:
Alloys are mixtures based on a metal.
Practice
Steel is an alloy of iron and:
Steel is iron + carbon.
Practice
Brass is an alloy of copper and ______.
Brass = copper + zinc.
What an alloy is
- An alloy is a mixture of a metal with one or more other elements.
- Examples: steel 钢 (iron + carbon), brass 黄铜 (copper + zinc), bronze 青铜 (copper + tin).
Different-sized atoms in an alloy stop the layers sliding, so it is harder
Practice
Alloys are harder than pure metals because the different-sized atoms:
Disrupted layers cannot slide, so the alloy is harder.
Why alloys are harder
- In a pure metal, layers of identical atoms slide easily, making it soft.
- Different-sized atoms in an alloy disrupt the layers, so they can't slide — making it harder.
Practice
Stainless steel contains chromium, which helps it resist rusting.
Chromium gives corrosion resistance.
Tailoring properties
- Alloying lets us tune properties: strength, hardness, corrosion resistance.
- Stainless steel 不锈钢 (with chromium) resists rust; this is why it's used for cutlery.
Example
Worked example. Pure iron is soft and bends easily. Adding a little carbon to make steel disrupts the atom layers, making it much harder and stronger — ideal for construction.
You've got it
Key idea
- an alloy is a metal mixed with other elements (steel, brass, bronze)
- different-sized atoms disrupt the layers, so alloys are harder than pure metals
- alloying tailors strength, hardness and corrosion resistance