FCC Nickel

Nickel (Ni), aside from being a monetary unit worth one twentieth of a dollar, is an element of atomic number 28. Nickel has an atomic weight of 58.71 and is almost always in a face-centered cubic crystalline lattice (discussed below).
The fact that a good many of the most corrosion-resistant alloys are of nickel base or contain considerable amounts of nickel is due not only to the corrosion-resisting and strengthening characteristics of nickel itself but more importantly to the fact that nickel is metallurgically compatible over a considerable composition range with a number of other metals such as copper, chromium, molybdenum, iron, and tungsten, which have some unique corrosion-resisting properties of their own. Nickel also can serve to bring together to some extent such metallurgically immiscible metals as copper and chromium in the same alloy, so that a considerable range of compositions is available, often as a single phase alloy. These alloys frequently have the austenitic face-centered cubic structure which is commonly associated with useful engineering properties. The high tolerance of nickel for alloying without phase instability is due largely to its favorable atomic size, its nearly filled third electron shell, and its face-centered cubic lattice structure.
Applications of nickel are many and varied. The monetary nickel coin constitutes roughly one percent of the nickel used in North America each year (and then, 75% is copper). Although pure (nominally) Nickel is sometimes used, materials are often plated with Nickel for its anti-corrosivity. Because of its electrical and magnetic properties, nickel is used in anodes and grids of televisions and ultrasonic transducers. Although a seemingly endless array of alloys are produced with Ni, 55 Nitinol is likely one of the most interesting. NIckel TItanium Naval Ordnance Laboratory is an alloy of titanium and nickel (53-57 wt %) that has a "memory." With a special heating and cooling treatment, 55 Nitinol can be mishaped and will return to its original shape given the proper conditions (namely temperature). This one alloy has a myriad of uses, including self-actuating fasteners, valves, safety devices (fire alarm), and stored energy devices (like jacks).
Nickel is highly crystalline, having an FCC structure as shown below. Ni has an atomic radius of 0.1246 nm and a lattice parameter of 3.52 Angstroms. (FCC also gives a coordination number of 12 and an atomic packing factor of 0.74) The image below shows the basic unit of the FCC. Note that the cube width, also the lattice parameter, is larger than the distance to the face-centered atoms.


Primitive Atomic structure: Face Centered Cubic VRML model.
If you have a VRML player, clicking on the above highlighted text will allow the exploration of the FCC structure in an interactive way.

The image below is the result of computer modeling of crack propagation in pure Nickel. The two highlighted regions below were chosen to illustrate different types of defects.s

Number 4. An analysis of local atomic distortions around a chosen defective region present in the given region.