Nicomet Spinodal Bronze has a distinct
advantage over other high strength copper alloys that have similar
mechanical properties.
The tin content of Nicomet attracts
the polar lubricant molecules
and this alloy performs better as bearings and wear plates than do
manganese bronzes and aluminum bronzes. Wear tests have proven that Nicomet wears
at less than half the rate of beryllium copper and aluminum bronze.
The Nicomet wear film, deposited on mating steel parts, results in very low
coefficients of sliding friction.
Aluminum bronze, manganese bronze and
beryllium copper all have abrasive precipitates or abrasive crystal phases
that are absent in Nicomet. Nicomet is a single phase alloy. The
strength comes from the spinodal structure, which is an ordered arrangement
of the nickel and tin atoms in waves only millionths of an inch in length.
The
precipitates or hard phases in the other copper alloys represent areas where
fatigue cracks will initiate. This limits their ability to withstand cycles
of bending or torsion loading. The single phase Nicomet is superior to
those alloys in fracture toughness.
Another attractive property of Nicomet
is its corrosion resistance. The tin and
nickel content of Nicomet makes it suitable for marine applications as well as the corrosive environments encountered
in oil and gas well drilling.
Nicomet spinodal bronze presents new possibilities to equipment designers when a combination of high
impact strength, fatigue resistance,
toughness, low wear and corrosion resistance is required.
The reason behind the excellent physical properties of spinodal
alloys was discovered
only after the invention of the electron microscope. Being able to view the microstructure
at 100,000 magnifications revealed a layered texture, the layers only being several atoms
in thickness. This structure is obtainable as a result of aging after solution treating to
cause what is called spinodal decomposition. The layers of slightly different composition
come from a movement of the solute atoms during the aging process. This small difference
is not a large scale diffusion to form precipitates which is the normal
strengthening action in precipitation hardening alloys. Spinodal decomposition is possible
when all the different metal atoms are nearly the same size and can form a completely
homogeneous solid solution. Since some spinodal alloys may actually create precipitates
upon slow cooling from the solid solution, it may be necessary to quench those metals from
the solid solution temperature. The desired atomic shift can then be effected by aging at
a lower temperature to allow the crystals to strengthen by atoms of one kind to move to
areas of higher concentration without forming a precipitate.
Since the strength of this alloys comes from its composition and heat treatment, it
is possible to make very large parts, with high strength, that can not be extruded, forged
or cold worked.
