Solid solution strengthening is a method to strengthen metals by dissolving alloying elements into the base metal's crystal lattice as substituional or interstitial solid solutions. There are three main factors that influence the degree of strengthening from solid solution strengthening: 1) The size difference between solute and solvent atoms, with larger differences creating more stress fields and strengthening; 2) The concentration of solute atoms, with higher concentrations creating more obstacles to dislocation movement; 3) The nature of distortion caused by the solute, with non-spherical interstitial distortions strengthening more than spherical substituional distortions. Solid solution strengthening increases the yield strength of metals.

1. TOPIC NO.- 8
SOLID SOLUTION
STRENGHENING
NAME- PAREKH JAYESH M.
ROLL NO. - 388

2. Why strengthening of metal is required?
As pure metal are inherently weak due to presence of
dislocation.
So, We can enhance the mechanical properties by eliminating
dislocation.
 So, by introducing some mechanism that prohibits the mobility of
dislocations, that are called Strengthing mechanism.
Methods For Strengthening Of Metal
(1)Strain hardening
(2)Grain boundary strengthening
(3)Solid solution strengthening
(4)Precipitation hardening

3. Solid Solution
• When the atoms of base metal (solvent) and the alloying elements
(solute) completely dissolve in each other and become an integral
part of the solid phase of alloy, the resulting phase is called a Solid
Solution.
Types of Solid Solution:
(1)Interstitial solid solution
(2)Substitutional solid solution

4. Interstitial Solid Solution
 Solute atoms are much smaller than solvent atoms, so they occupy
interstitial position in solvent lattice.
 Carbon ,nitrogen ,hydrogen ,oxygen and boron are the element
which commonly form interstitial solid solution.

5. Substitutional Solid Solution
 Solute atoms sizes are roughly similar to solvent atoms.
 Due to similar size solute atoms occupy vacant site in solvent atoms.
 Copper and zinc, copper and nickel, are the example of substitutional
solid solution.

6. Hume Rothery’s Rule
Hume rothery studied a number of alloy systems and formulated
condition that favour extensive substitutional solid solubility.
Three conditions of Hume Rothery’s rule
(1)The size difference between solute and solvent atoms must be less
than 15%
(2)The crystal structure of metal must be same.
(3)The electronegativity difference between the metal must be small.
Strengthening Mechanisms Depends On,
 Difference in size between solute and solvent atoms
 Amount of solute added,
 Nature of distortion produced by solute atoms.

7. How This Parameter Affect Strengthening Mechanisms.
(1)As the size difference between solute and solvent atoms increases ,
the intensity of stress field around solute atom increases and
resistance to dislocation is increases, so strength of metal is also
increases.
(2)A large concentration of solute atoms are added it means more
frequent obstacles to dislocation. The strength increases in
proportion of C ½, where c is a concentration of solute atoms.
(3)The nature of distortion produced by solute atoms are also
important.
 Spherical distortion produced by Substituional solute atoms.
 Non spherical distortion produced by interstitial solute atoms.
 Non spherical distortion produced maximum effect i.e. it increases
yield strength.

8. Results of Solid Solution Strengthening

9. Effect of solute alloy additions on stress-strain curve

10. THANK YOU….