Crystal Structures for Metallic Elements

The crystals of most metals have highly symmetrical structure. The most common types of lattices are (a) Body Centred Cubic Structure (BCC) (b) Face Centred Cubic Structure (FCC) (c) Hexagonal Close Packed Structure (HCP) Body Centred Cubic Structure (BCC) – In this type of structure, atoms are located at the corners of the cube and one atom at its centre. This type of unit cell is found in metals like lithium, sodium, potassium, barium, vanadium etc. Face Centred Cubic Structure (FCC) – In this type of structure, atoms are located at the…

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Basic Modes of Plastic Deformation – Deformation by Slip & Deformation by Twinning

Deformation by Slip Slip is defined as sliding of blocks of crystal over one another along definite crystallographic planes called slip planes. So it is the relative displacement along a definite direction. When slip takes place, one part of the lattice moves with respect to the other. Generally slip plane is the plane of highest atomic density and slip direction is the closest packed direction within the slip plane. This is because the bond between these planes is weakest, so when force is applied in proper direction, relative movement takes place very easily. The shear stress…

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