Copper Alloys - Nickel Silvers

Topics Covered

Background

Key Properties

Applications

Electrical Contacts

Gift And Tablewares

Mechanical Connectors

Other Applications

Background

These are alloys of copper, nickel (10 to 25%) and zinc (17 to 40%). While they contain no silver, they owe their name to the silvery white colour they possess. The whitest alloys possess higher nickel contents.

Similar to brasses, depending on the actual composition, nickel silvers may be either single (alpha) phase or two phase (alpha-beta).

Lead may be added to increase machinability but results in some loss of cold workability.

Key Properties

•        Good corrosion resistance

•        Excellent spring properties at elevated temperatures

•        Strength increases with nickel content with ductility remaining almost unchanged

•        Corrosion resistance increases with nickel content and are less susceptible to stress corrosion compared to copper zinc alloys.

•        Electrical conductivity is only a fraction of that of copper

Alpha alloys are ductile and can be easily worked at room temperature.

Alpha-beta alloys cannot be worked at room temperature, but are easily hot worked

Applications

Electrical Contacts

Nickel silvers are used for electrical contacts in the electronics and telecommunications industries.

Gift And Tablewares

In this application, the items are often plated with silver. The natural colour and resistance of this alloy to tarnishing means that even when the silver wears off, the item still retains an attractive appearance.

Mechanical Connectors

Due to the favourable strength properties and excellent corrosion resistance, nickel silvers are used for applications such as clips, rivets, screws, hinges and locks.

Other Applications

Other applications include springs, instrument parts, architectural fittings, machined parts, decorative items, resistance wire, musical instrument wire, camera parts.

Primary author: Dr. Agnes Sagal

Source: Materials Information Service, “Using copper and copper alloys” edited by Justin Furness, printed by The Institute of Materials.

 

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