Nickel, alloys with copper crystal structure

Metal alloys can be amorphous, too. LiquidmetaF alloy is an amorphous alloy of zirconium mixed with nickel, titanium, copper, and beryllium. It is used in the heads of some brands of golf clubs. Traditional metal club heads may have microscopic gaps where planes of metallic crystals meet. These tiny gaps are a potential source of weakness. The amorphous alloy is non-crystalline, so the metal structure does not have potential breakage sites. 

Substitution of one atom for another is a common phenomenon. These mixtures are also called solid solutions. For example, nickel and copper atoms have similar sizes and electronegativities and the same fee crystal structures. Mixtures of the two are stable in any proportion, with random arrangement of the atoms in the alloys. Other combinations that can work well have a very small atom in a lattice of larger atoms. In this case, the small atom occupies one of the interstices in the larger lattice, with small effects on the rest of the lattice but potentially large effects on behavior of the mixture. If the impurity atoms are larger than the holes, lattice strains result and a new solid phase may be formed. 

Kharchenko, O.I., 1977, Investigation of the ternary systems of yttrium, cerium and lanthanum with iron, cobalt, nickel and copper phase equilibria, crystal structures and some physical properties of the alloys, Ph.D. Chemistry thesis, 1977, Lvov (Lvov State University, Lvov) pp. 1-20. 

When we determined the crystalline structure of solids in Chapter 4, we noted that most transitional metals form crystals with atoms in a close-packed hexagonal structure, face-centered cubic structure, or body-centered cubic arrangement. In the body-centered cubic structure, the spheres take up almost as much space as in the close-packed hexagonal structure. Many of the metals used to make alloys used for jewelry, such as nickel, copper, zinc, silver, gold, platinum, and lead, have face-centered cubic crystalline structures. Perhaps their similar crystalline structures promote an ease in forming alloys. In sterling silver, an atom of copper can fit nicely beside an atom of silver in the crystalline structure. 

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