Copper Alloys - Copper/Nickel Alloys
Sometimes called cupro-nickels, there exists a range of different copper nickel alloys that possess different properties and hence are suited to a range of different applications. Some of the better known copper nickel alloys include:
- Copper with 10% nickel
- Copper with 30% nickel
- Copper with 25% nickel with 0.05-0.4% manganese
- Copper with 45% nickel (also known as constantan)
All copper nickel alloys consist of only one phase as the copper nickel binary system exhibits complete solid solubility.
Properties of copper nickel alloys vary with composition, however, some properties of copper nickel alloys are outlined below.
Copper-Nickel alloy Copper 90/10 and Copper 70/30
- Outstanding resistance to corrosion, particularly sea water
- 70/30 is stronger and has superior resistance to impingement corrosion
- Good resistance to biofouling, with the 90/10 alloy being slightly superior compared to the 70/30 alloy
Copper rich alloys are:
- Can be hardened only by cold working
- Good corrosion resistance
- Good strength
- Low temperature co-efficient of electrical resistance
The nickel content in these copper nickel alloys also enables them to retain their strength at elevated temperatures compared to copper alloys without nickel.
Applications of Copper Nickel alloys
Due to the good resistance to sea water corrosion, the copper nickel alloy Copper 90/10 and copper nickel alloy Copper 70/30 are employed for sea water condenser systems and in desalination plants, as well as pipe work in chemical plants.
Due to the fact that the copper nickel alloy Copper 90/10 requires no surface protection and hence gives extra safety, this copper nickel alloy is being increasingly employed for brake and hydraulic suspension systems and cooling systems in cars and commercial vehicles.
The good resistance to biofouling and sea water corrosion resistance of the copper nickel alloys, Copper 90/10 and Copper 70/30 alloys have lead to its use in applications such as cladding for ships' hulls, legs of oil rig platforms and sea water intake screens.
The copper nickel alloys composed of copper with 25% nickel with 0.05-0.4% manganese is commonly used for the manufacture of coins, medals and other semi valuable applications.
Due to the very low temperature co-efficient of electrical resistivity, the copper nickel alloys composed of copper with 45% nickel alloy is used for resistance wire in high precision resistors. This property of copper nickel alloys allows the resistor to operate at almost exactly the same resistance regardless of temperature.
The copper nickel alloys composed of copper-45% nickel alloy is also used for thermocouples as it develops a high and uniform EMF when coupled with other metals such as copper and iron.
Copper nickel alloys are also used in cooling circuits, ammunition, sea water corrosion-resistant assemblies, condenser tubes.
Property Table of Copper Nickel Alloys
Material: Copper Alloys - Copper Nickel Alloys
|Property||Minimum Value (S.I.)||Maximum Value (S.I.)||Units (S.I.)||Minimum Value (Imp.)||Maximum Value (Imp.)||Units (Imp.)|
|Atomic Volume (average)||0.0071||0.0073||m3/kmol||433.268||445.473||in3/kmol|
|Bulk Modulus||130||170||GPa||18.8549||24.6564||106 psi|
|Modulus of Rupture||85||550||MPa||12.3282||79.7708||ksi|
|Shear Modulus||45||58||GPa||6.5267||8.41219||106 psi|
|Young's Modulus||120||156||GPa||17.4045||22.6259||106 psi|
|Latent Heat of Fusion||220||240||kJ/kg||94.5825||103.181||BTU/lb|
|Maximum Service Temperature||425||480||K||305.33||404.33||°F|
|Minimum Service Temperature||0||0||K||-459.67||-459.67||°F|
|Resistivity||11.7||36.3||10-8 ohm.m||11.7||36.3||10-8 ohm.m|
|Oxidation at 500C||3|