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In the diagram on the right, the specific plane and direction are (111) and [1 10], respectively. Given the permutations of the slip plane types and direction types, fcc crystals have 12 slip systems. [3] In the fcc lattice, the norm of the Burgers vector, b, can be calculated using the following equation: [4]
The most intense diffraction peak from a material that crystallizes in the FCC structure is typically the (111). ... (planar) lattice. ... is the probability density ...
The FCC and HCP packings are the densest known packings of equal spheres with the highest symmetry (smallest repeat units). Denser sphere packings are known, but they involve unequal sphere packing. A packing density of 1, filling space completely, requires non-spherical shapes, such as honeycombs.
Comparison of fcc and hcp lattices, explaining the formation of stacking faults in close-packed crystals. In crystallography, a stacking fault is a planar defect that can occur in crystalline materials. [1] [2] Crystalline materials form repeating patterns of layers of atoms. Errors can occur in the sequence of these layers and are known as ...
[4] [5] The bcc and fcc, with their higher densities, are both quite common in nature. Examples of bcc include iron, chromium, tungsten, and niobium. Examples of fcc include aluminium, copper, gold and silver. Another important cubic crystal structure is the diamond cubic structure, which can appear in carbon, silicon, germanium, and tin.
In face centered cubic (FCC) metals, screw dislocations can cross-slip from one {111} type plane to another. However, in FCC metals, pure screw dislocations dissociate into two mixed partial dislocations on a {111} plane, and the extended screw dislocation can only glide on the plane containing the two partial dislocations. [ 2 ]
A stacking fault is an irregularity in the planar stacking sequence of atoms in a crystal – in FCC metals the normal stacking sequence is ABCABC etc., but if a stacking fault is introduced it may introduce an irregularity such as ABCBCABC into the normal stacking sequence. These irregularities carry a certain energy which is called the ...
Since the dislocation density increases with plastic deformation, a mechanism for the creation of dislocations must be activated in the material. Three mechanisms for dislocation formation are homogeneous nucleation, grain boundary initiation, and interfaces between the lattice and the surface, precipitates, dispersed phases, or reinforcing fibers.