Alloys are mixtures of two or more metals or substances with metallic properties. When a molten mixture of metals cools below the melting point, one of four things can occur: 1) a solid solution forms where the metals remain soluble in each other, 2) the metals are insoluble and susceptible to corrosion, 3) the metals are partially soluble forming two types of grains, or 4) the metals form intermetallic compounds that are hard, brittle, and have low ductility. Solid solutions are generally harder, stronger, and more elastic than the pure metals.

1.  Alloys are the mixture of two or more
metals or substances with metallic
properties
 Binary Alloys - Mixture of two Alloys
 Ternary Alloys - Mixture of three
Alloys

2.  PROPERTIES
 In molten state usually slow mutual
solubility when the molten mixture is
cooled to below
 the melting point one of four things occur:
 (1) The component metals may remain
soluble in each other forming solid
solution.

3. There are three forms of solid
solutions.
* Random Solid Solution :
component
metals atoms occupy random sites in a
common crystal lattice.
* Ordered Solid Solution :
Component
metals atoms occupy specific sites in a
common crystal lattice.

4.  * Interstitial Solid Solution :

For binary alloys, the primary
lattice sites are occupied by
one metal atoms of second
component do not occupy
lattice sites but lie within the
interstices of the lattice.

5.  solid solutions are generally
harder, stronger and have high value of
elastic than the pure metals from
which they are derived.
 (2). The component metals may be
completely insoluble in the solid state
this type of alloys are susceptible to
electrolytic corrosion. Complete
insolubility of two metal is rarely
encountered in practice.

6. (3).The two metals
may be partially
soluble in the solid
state. There is limit to
the solubility of two
metals one the other
in each of the two
types of grain

7. (4). If the two metals
show a particular
affinity for one another
they may form inter
metallic compounds
with precise chemical
formulation. Such
material are relatively
hard and brittle with
low ductility