AgCu

AgCu refers to a class of binary alloys composed of silver (Ag) and copper (Cu). In practical use, AgCu denotes silver-copper alloys with limited solubility of copper in silver. The most familiar example is sterling silver, which typically contains about 92.5% silver and 7.5% copper. The Ag–Cu system features a eutectic composition near 28 weight percent copper, which can form a characteristic lamellar microstructure and a melting point around 779°C.

Properties of AgCu alloys vary with copper content. Adding copper strengthens and hardens silver, increasing strength and hardness at the expense of some ductility. The color becomes warmer or slightly yellowish as copper content rises. Electrical conductivity remains high but decreases with added copper, compared with pure silver. Tarnish and patina behavior is influenced by copper content, with higher copper levels generally promoting more pronounced surface coloration and tarnish in some environments. Corrosion resistance is similar to silver, though alloy composition can affect surface reactions.

Production and use. AgCu alloys are widely used in jewelry, with sterling silver (925 Ag) being the standard reference alloy. They are also employed in some electrical contact materials and in various brazing and soldering filler metal applications, where a balance of conductivity, strength, and corrosion resistance is desirable. Processing typically involves melting, alloying, and subsequent work hardening or heat treatment to achieve the desired combination of properties.

See also: Sterling silver, silver–copper phase diagram, electrical contact materials.