Face-Centered Cubic (FCC)

Published: | Updated: February 14, 2020;

Definition - What does Face-Centered Cubic (FCC) mean?

Face-centered cubic (fcc or cF) refers to a crystal structure consisting of an atom at each cube corner and an atom in the center of each cube face.

It is a close-packed plane in which on each face of the cube atoms are assumed to touch along face diagonals. A face-centered cubic crystal structure exhibits more ductility (deforms more readily under load before breaking) than a body-centered cubic (bcc) structure.

Face-centered cubic is also known as cubic close-packed (ccp).

Corrosionpedia explains Face-Centered Cubic (FCC)

Metals with the fcc structure include:

  • Aluminum
  • Copper
  • Nickel
  • Gamma iron
  • Gold
  • Silver

The face-centered cubic system is closely related to the hexagonal close-packed system. The two systems differ only in the relative placements of their hexagonal layers. The plane of a face-centered cubic system is a hexagonal grid.

The atomic packing factor is 0.740 in fcc. The fcc value is the highest theoretically possible value for any lattice, although there are other lattices which also achieve the same value, such as hexagonal close-packed and one version of tetrahedral bcc.

It is significant that the sides of the face-centered cube, or the distances between neighboring lattices in the fcc arrangement, are about 25 percent larger than in the bcc arrangement; this means that there is more space in the fcc than in the bcc structure to keep foreign (i.e., alloying) atoms in solid solution.

Slip in fcc crystals occurs along the close-packed plane. The fcc crystals have 12 slip systems. In fcc, stacking fault energy can vary from very low values to very high values. Regarding lattice defects in plasticity, fcc is not a homogeneous structure.

In fcc metals, the flow stress (the force required to move dislocations) is not strongly temperature dependent. Therefore, dislocation movement remains high even at low temperatures and the material remains relatively ductile.

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