Different types of crystal structures in metal

This blog page can be used for a last minute revision on the topic of ' Different types of crystal structures in metal' from the material science course.

Different types of crystal structures in metal

- There are 3 types of  crystal structures in metals . They are Face- centered cubic (FCC) , Body - centered cubic ( BCC ) and Hexagonal close packed ( HCP ) .

Keywords

 Crystalline 

- It is a material in which the atoms positioned in a repeating or a periodic array over the large atomic distances.

Crystal structure

- It is the manner in which the atoms , ions or molecules are spatially arranged .Well , there is an extremely large number of different crystal structures that comprises a long range atomic order which varies from simple structures for metals to complex ones which are being displayed by some of the ceramic and polymeric materials.

Lattice 

- It is a model which a three- dimensional array of points coinciding with the atom positions.

Face- Centered Cubic ( FCC)

Face-Centered Cubic in a unit cell

- This lattice is a cubic shape.

- There are 8 corner atoms in each unit cell and also 6 atoms on each face of the unit cell .

- The effective total number of atoms in a face-centered cubic unit cell is 4.

Body- Centered Cubic

Body-centered cubic

                                                         

- This lattice is a cubic shape.

- There are 8 corner atoms in each unit cell and 1 centre atom is each unit cell .

- The effective total number of atoms in a body-centered cubic is 2 .

Hexagonal Close- Packed Crystal Structures

- This lattice is in a hexagonal shape .

- The hexagonal plane is also known as a  basal plane.

- The top and bottom basal plane consist of 6 corner atoms.

- In the mid plane , it consist of 3 atoms .

- At the centre of the upper and lower basal planes , there is one atom .

Linear Density

- It is defined where the number of atoms per unit length where the centers lies on the direction vector for a specific crystallographic structure.

LD = Number of atoms centered on direction vector 

          length of direction vector

Planner Density

- Planner density is the number of atoms per unit area that are centered on a crystallographic plane.

PD =  Number of atoms centered on a plane 
            Area of plane