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to Metals
to Copper alloys
Dr. Dmitri Kopeliovich
According to the Unified Numbering System (UNS):
Copper-Nickel Alloys (Copper-Nickels, Cupro-nickels) are copper alloys, containing 1.5-45% of nickel (Ni) as the major alloying element. Wrought Copper-Nickel alloys are designated with the numbers from C70000 through C73499.
Wrought Copper-Nickel alloys may contain up to 8% of tin (Sn), up to 4.5% of manganese (Mn), up to 2% of iron (Fe), up to 2.5% of chromium (Cr) and up to 1% of silicon (Si) as additional alloying elements.
Copper-nickel-zinc alloys form a separate group called nickel silvers.
Copper-Nickel-Zinc Alloys (Nickel Silvers) are copper alloys containing 8-25% of nickel (Ni) and 17-45% of zinc (Zn) as the major alloying elements. Wrought Copper-Nickel-Zinc alloys are designated with the numbers from C73500 through C79999.
Wrought Copper-Nickel-Zinc alloys may contain up to 6% of manganese (Mn) as additional alloying element.
Copper-Nickel alloys and most of Copper-Nickel-Zinc alloys have mono-phase structure (α-phase) and possess very good formability in cold and hot states.
Wrought Copper-Nickel alloys have moderate mechanical strength and high ductility combined with very good corrosion resistance (particularly in sea water).
Iron, manganese and chromium are added to the wrought Copper-Nickel alloys for increasing their hardness and strength.
The alloys are strengthened by cold work (strain hardening). Ductility of the alloys decreases as a result of cold work.
Separate group of copper-nickel alloys is Spinodal Bronzes: copper-nickel-tin alloys possessing high mechanical strength due to a controlled heat treatment called Spinodal decomposition.
Copper-Nickel alloys are used for manufacturing coins, sea water equipment, evaporators, heat exchanger tubes, automotive hydraulic and cooling systems.
Copper-Nickel alloys (Nickel Silvers) are used in decorative applications and for manufacturing resistance wire, optical parts, screws, rivets, clips, tableware, electrical contacts.
| UNS Designation | Trade mark | Ni,% | Zn,% | Mn,% | Fe,% | Cu,% |
|---|---|---|---|---|---|---|
| C70400 | Copper-Nickel 5% | 4.8-6.2 | 1.0 max. | 0.3-0.8 | 1.3-1.7 | balance |
| C70600 | Copper-Nickel 10% | 9.0-11.0 | 1.0 max. | 1.0 max. | 1.0-1.8 | balance |
| C71000 | Copper-Nickel 20% | 19-23 | 1.0 max. | 1.0 max. | 1.0 max. | balance |
| C71500 | Copper-Nickel 30% | 29-33 | 1.0 max. | 1.0 max. | 0.4-1.0 | balance |
| C74500 | Nickel Silver 65-10 | 9.0-11.0 | balance | 0.5 max. | 0.25 max. | 63.5-66.5 |
| C75200 | Nickel Silver 65-18 | 16.5-19.5 | balance | 0.5 max. | 0.25 max. | 63.0-66.5 |
| C75400 | Nickel Silver 65-15 | 14.0-16.0 | balance | 0.5 max. | 0.25 max. | 63.5-66.5 |
| C75700 | Nickel Silver 65-12 | 11.0-13.0 | balance | 0.5 max. | 0.25 max. | 63.5-66.5 |
| C77000 | Nickel Silver 55-18 | 16.5-19.5 | balance | 0.5 max. | 0.25 max. | 53.5-56.5 |


