Nickel is a hard, tough, and malleable silver-white metal that is highly resistant to oxidation and corrosion.  Nickel is also magnetic.  It is principally used in combination with other elements to impart strength, toughness, and corrosion resistance to many different ferrous and nonferrous alloys.

    Nickel is of tremendous importance in the production of austenitic stainless steels and alloy steels.  Its addition to steels improves corrosion resistance, strength, fabricability, and ductility.  Stainless steels are widely utilized in products and equipment for the process, chemical, energy, and transportation industries.  Alloy steels are used in the automotive, construction, and machinery industries for parts requiring high strength and wear resistance.  Also, because nickel lowers the ductile-to-brittle transition temperature of steel, alloy steels containing nickel are often used to transport and handle liquefied gases and for machinery and structures operated at subzero temperatures.

    Nonferrous alloys also often contain nickel in their composition.  Just as in steels, nickel increases the corrosion and heat resistances for nonferrous alloys.  Important applications of nonferrous alloys occur in the transportation, power, process, chemical, and electronics industries.  Also, nickel-base superalloys are used for advanced propulsion systems such as jet engines.

    Another important application is nickel electroplating.  Nickel plating improves appearance, surface finish, and corrosion / wear resistance.  Products that are typically electroplated with nickel include automobile parts and consumer appliances.  Additional miscellaneous uses of nickel include catalysts, coinage, and permanent magnets.

    For additional information on nickel, visit the linked web sites that follow.

 WebElements:  Nickel

 Nonferrous Metals:  Section 1.6 Nickel

Nickel Crystal Structure Summary

    A perfect lattice of pure nickel is face-centered cubic with a lattice parameter of 3.52 Angstroms.  Fourteen nickel atoms create one cubic unit.  In the fcc crystal structure, an atom is positioned at each corner and at the center of each face of the cube.

    The face-centered cubic unit is defined by four sublattices, i.e. four unique nickel atom positions.  General terminology and coordinates (using the coordinate system presented at left) of these atoms are:  1) corner atom at (0,0,0), 2) xy plane center atom at (1.76,1.76,0), 3) xz plane center atom at (1.76,0,1.76), and 4) yz plane center atom at (0,1.76,1.76).  The lattice parameter of 3.52 Angstroms is the length of an edge of a cube unit.  Therefore, a distance of 1.76 Angstroms corresponds to one half of a unit along an edge of the cube.  Also notice the bonds stemming off of each of the atoms.

    Again, one comple face-centered cubic unit of nickel is composed of fourteen atoms as presented at right; however, there are four atoms with unique postion types while the other ten atoms are just repeated position types.  The coordination number, another important characteristic in describing crystal structure, for the fcc model is 12.  This means that each atom has twelve nearest neighboring atoms.  A central face atom, say in the yz plane, has four corner nearest neighbors, four face atoms in contact from behind within the cube, and four equivalent face atoms from an equivalent fcc unit exactly adjacent with the yz plane.

    Images of the face-centered cubic structure shown above were taken from a web page discussing solid state physics prepared by Ralf Vogelgesang from the Physics Department at Purdue University.  The images were modeling monatomic copper in his usage.  However, they also sufficiently model the nickel fcc structure for our case.
 

Nickel Sample Crystal Structure Analysis

Click here to view a three-dimensional model.

    Inspection of the piece of the nickel sample presented above reveals two layers.  One to the front and a second to the back.  Looking at the front layer, a pattern is obvious.  One may see one side of an fcc structure, with four corner atoms and a central face atom, repeated over and over.  Then the layer in the background would correspond to face center atoms projected at 1.76 Angstroms back from the plane containing the atoms in the foreground.  Of course, one may look at this vice-versa with the background nickel atoms composing four corners of a face and a central atom of the same face for several repeated units and the foreground layer forming central face atoms.  Below one can see that our sample is a thin film sample only containing two layers in one direction.  Again, the fcc structure is visible justified by the same arguements from above.

 

Complete Sample Defects Summary

Nickel sample wire frame model.

    Defects observed from a general analysis of the entire sample include a growing crack, dislocations, and vacancies.  The growing crack is evident as its tip protrudes the heart of the sample.  Dislocations have caused open spaces and misconfigurations to occur throughout the sample.  Grain boundaries divide regions of varying orientations.  Vacancies appear as holes in the nickel lattice.
 

Local Distortions Within a Random Subsample

    A random section of the entire nickel sample has been selected and isolated for further, more detailed analysis.  This section is presented below and a link is provided for three-dimensional model viewing.  To view the three-dimensional model, click on the image.

    Grain boundaries divide the subsample into three distinguishable regions: an upper left, an upper right, and a lower region.  The boundary lines themselves are visible from the differing orientations of the regions noted and the holes that have resulted from the large dislocation of nickel atoms or possibly the removal of an atom (vacancy).  The crystal structure of the upper left region is still mostly preserved as is the upper right region particularly just inwards from the corners.  However, approaching the grain boundaries, the perfect lattice structure starts to break down and atoms appear dislocated.  The bottom region has extreme dislocation of atoms.  The fcc structure can not be identified anywhere throughout this region.  In fact, no pattern is really identifiable.  The atoms of this lower region seem to have aligned themselves at approximately 30 degrees off the horizontal.  The upper left and the upper right region are orientated at approximately 19 degrees off of each other.
 

References

Callister, William D., Jr. Materials Science and Engineering an Introduction.  4th ed.  New York:  John Wiley & Sons, 1997.

Pasquine, Donald L.  Metals Handbook.
 
 

Direct comments and questions to jconner@vt.edu.