Chemistry Form 4: Chapter 9 Alloys

ALLOYSNor Adilah binti Muhd Soffian Wong

Siti Sarah binti Mohd Fadlee LeeNursyazwani Binti RoslanSuhaila binti Mohamed

4 MUTIARA

WHAT IS ALLOY ???

What is alloy ?

• Alloy is a mixture of two or more elements with a certain fixed composition in which the major component is a metal

THE AIM IN MAKING ALLOYS

•To increase the hardness and strength of metal

•To prevent corrosion or rusting•To improve the appearance of

the metal surface

EXAMPLE OF ALLOYS

Example of alloys• Bronze• Brass• Steel• Stainless steel• Duralumin• Pewter

PROPERTIES OF ALLOYS

ALLOY COMPOSITION PROPERTIES USES

Bronze ~ 90% copper

~ 10% tin

~ Hard and strong

~ Does not corrode easily

Has shiny surfaces

~ to build statues and monuments

~ in the making of swords, medals and artistic materials

Brass ~ 70% copper

~ 30% zinc

~ Harder than copper ~ in the making of musical instruments and kitchenware

Steel ~ 99% iron

~ 1% carbon

~ Hard and strong ~ in the construction of building and bridges

~ in the building of cars and railway tracks

Stainless steel ~ 74% iron

~ 8% carbon

~ 18% chromium

~ shiny

~ strong

~ does not rust

~ to make surgical instruments

Duralumin ~ 93% aluminium

~ 3% copper

~ 3% magnesium

~ 1% maganese

~ light

~ strong

~ to make the body of aeroplanes

and bullet trains

Pewter ~ 96% tin

~ 3% copper

~ 1% antimony

~ luster

~ shiny

~ strong

~ in the making of souvenirs

THE ARRANGEMENT OF ATOMS IN PURE METALS

When force is applied, layers of atoms in pure

metal slide. So, metals are ductile.

There are empty space between the atoms. When it is knocked, the shape of the metal changes.

So, metals are malleable.

ARRANGEMENT OF ATOM IN ALLOYS

The presence of atoms of other metals that are of different sizes disturb the orderly arrangement of atoms in the metal. This reduces the layer of atoms from sliding. Thus, an alloy

is stronger and harder than its pure metal