Notes On Alloys - ICSE Class 10 Chemistry

An alloy is a homogeneous mixture of two or more metallic  solutions.
One of the elements in the alloys is essentially a
metal, while the other element or elements may be metals or non-metals like carbon, silicon, sulphur or boron.
Alloy = Metal + metal/non-metal(C, Si, S, B)

Pure metals have poor mechanical properties. Hence, they are not used in their pure form in industry. Their properties are modified by adding other elements.
Alloys are often made to alter the mechanical properties of the base metal. For example, to induce hardness, toughness, ductility, or other desired properties.


Characteristics of alloys
Alloys are harder and tougher than the base metal and are resistant to corrosion.
They are inert to commonly used chemicals and are magnetisable and ductile.

Some important alloys

Name of the Alloy Composition Uses
Brass Cu: 80%
Zn: 20%
In making of utensils, pipes and radiator statues etc
Bronze Cu: 90%
Sn: 10%
In making of coins, ornaments, utensils and statues
Stainless steel Fe: 82%
(Ni + Cr): 18
In making of surgical instruments, watches and utensils etc
Magnalium Al: 95%
Mg: 5%
In making light articles and physical balance etc
Duralumin Al: 95%
Cu: 4%
Mn: 0.5%
In making parts of aeroplane and ship etc
German silver Cu: 60%
Zn: 20%
Ni: 20%
It is useful in electroplating and making of utensils
Gun metal Cu: 88%
Sn: 10%
Zn: 2%
It is useful in making of guns, machine parts and canons..etc
Solder metal Pb: 50%
Sn: 50%
It is mainly useful to join electric wires 



Alloyed gold
The purest form of gold, 24- carat gold, is very soft and cannot be moulded into jewellery because of this reason copper or silver is added to it to lend it hardness and strength.
About 8.4% copper or silver is added to 24 carat gold to convert it into 22 carat gold, with a purity of about 91.6%  Jewellery is mostly made in 22 carat gold.

Summary

An alloy is a homogeneous mixture of two or more metallic  solutions.
One of the elements in the alloys is essentially a
metal, while the other element or elements may be metals or non-metals like carbon, silicon, sulphur or boron.
Alloy = Metal + metal/non-metal(C, Si, S, B)

Pure metals have poor mechanical properties. Hence, they are not used in their pure form in industry. Their properties are modified by adding other elements.
Alloys are often made to alter the mechanical properties of the base metal. For example, to induce hardness, toughness, ductility, or other desired properties.


Characteristics of alloys
Alloys are harder and tougher than the base metal and are resistant to corrosion.
They are inert to commonly used chemicals and are magnetisable and ductile.

Some important alloys

Name of the Alloy Composition Uses
Brass Cu: 80%
Zn: 20%
In making of utensils, pipes and radiator statues etc
Bronze Cu: 90%
Sn: 10%
In making of coins, ornaments, utensils and statues
Stainless steel Fe: 82%
(Ni + Cr): 18
In making of surgical instruments, watches and utensils etc
Magnalium Al: 95%
Mg: 5%
In making light articles and physical balance etc
Duralumin Al: 95%
Cu: 4%
Mn: 0.5%
In making parts of aeroplane and ship etc
German silver Cu: 60%
Zn: 20%
Ni: 20%
It is useful in electroplating and making of utensils
Gun metal Cu: 88%
Sn: 10%
Zn: 2%
It is useful in making of guns, machine parts and canons..etc
Solder metal Pb: 50%
Sn: 50%
It is mainly useful to join electric wires 



Alloyed gold
The purest form of gold, 24- carat gold, is very soft and cannot be moulded into jewellery because of this reason copper or silver is added to it to lend it hardness and strength.
About 8.4% copper or silver is added to 24 carat gold to convert it into 22 carat gold, with a purity of about 91.6%  Jewellery is mostly made in 22 carat gold.

References

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