INTRODUCTION
An alloy is a homogenous mixture of 2 or more metals or a
non-metal.
Example: amalgam-alloy of mercury with another metal.
Alloy are used in some applications, where their properties are
superior to those of the pure component elements for a given
application.
Examples of alloys are steel, solder, brass, pewter, duralumin,
phosphor bronze and amalgams. The alloy constituents are
usually measured by mass.
Alloys are usually classified as substitution or interstitial alloys,
depending on the atomic arrangement that forms the alloy.
Alloys are usually harder than their components but very often
less ductile and less malleable.
Thus the hardness of gold is increased by addition of copper
to it. The melting point of an alloy is always lower than the
melting points of the constituent’s metals. Other properties
such as reactivity towards atmospheric oxygen and moisture,
mechanical strength, ductility, color etc. also undergoes a
change when an alloy is made from its constituents (metals)
This change of properties is very useful and makes an alloy
beneficial
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REVIEW OF LITERATURE
Some of the commonly used alloys along with their
composition are given below.
Brass:-
Copper:50-90% zinc:20-40%
Small amount of tin, lead and iron.
Bronze:
Copper:60-90% tin:5-35%
Small amount of lead, zinc and iron.
Gun metal:
Copper:85-90% zinc:1-3% tin:8-12%
Some common alloys
Brass
Brass is an alloy made of copper and zinc. The proportions of
zinc and copper can vary to create different types of brass
alloys with varying mechanical and electrical properties. It is
a substitution alloy; atoms of the two constituents may replace
each other within the same crystal structure.
In contrast, bronze is an alloy of copper and tin.
Combination of iron, aluminium, silicon and manganese make
brass resistant to wear and tear.
Bronze
Bronze is an alloy consisting primarily of copper and the addition
of other metals (usually tin) and sometimes arsenic, phosphorus,
aluminum, manganese and silicon. These additions produces an
alloy much harder than copper alone.
The historical period where the archaeological
record contains many bronze artefacts is known
as the bronze age.
Because historical pieces were often made of brasses(copper
and zinc) and bronzes with different compositions, modern
museum and scholarly descriptions of older objects increasingly
use the more inclusive term “copper alloy” instead.
Bronze has myriad uses in industry. It is widely used totally for
springs, bearings, bushings and similar fittings and is particularly
common in the bearings of small electric motors.
It is also widely used for cast metal sculpture and is most
popular metal for top quality bells and cymbals. Commercial
bronze, otherwise known as brass, is 90% copper and 10% zinc.
It contains no tin.
RUST:- For a layman, rust is a brown solid that
appears because of the oxidation of iron due to
the presence of oxygen and moisture in the air.
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