Fcc Bcc Hcp Structures

Engineering Materials
Assignment #1
BCC, FCC, HCP Cell structures
Submission Date: Thursday 10th October 2013 Due date: Thursday 10th October 2013

Using plastic balls, Velcro and UHO we build the three common closepacked structures for metallic materials : * Body Centered cubic (BCC) * Face Centered cubic (FCC) * Hexagonal closed pack (HCP) As we know these atoms are held together by metallic bonds. The crystal structure is called “Lattice”. - We couldn’t use Super glue to connect the plastic balls because; super glue with plastic generates a chemical reaction which melts the plastic. - Body Centered Cube (BCC) : Least closely packed

It consists of 4 atoms on the first layer , one atom on the second layer and another 4 atoms on the third layer.(all sides of the same length and all face perpendicular to each other) with an atom at each corner of the unit cell and an atom in the center of the unit cell.) At room temperatures, elements Li, Na, K, Rb, Ba, V, Cr and Fe have structures that can be described as body centre cubic (bcc) packing of spheres.

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- Face Centered Cube (FCC) :

FCC Metals tend to be ductile: Most packed.
It consists of 5 atoms on the first layer , four atoms on the second layer, and another 5 atoms on the third layer. (The face-centered cubic unit cell is a cube (all sides of the same length and all face perpendicular to each other) with an atom at each corner of the unit cell and an atom situated in the middle of each face of the unit cell.) FCC Metals Like: Cu, Au, Ag, Al, . Usually soft and ductile.

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- Hexagonal Close Packed (HCP) :

The hexagonal closest-packed structure is described by a hexagonal unit cell, which has a diamond shaped or hexagonal base with sides of equal length (a = b). The base is perpendicular to the longest side (length c)) of the unit cell. An atom is centered on each corner of the unit