CuSn

CuSn refers to a binary alloy of copper (Cu) and tin (Sn). The most familiar material in this family is bronze, a copper-tin alloy that has been used for millennia. Tin is typically added in amounts from roughly 5% to 20% by weight; varying tin content changes the alloy’s microstructure and properties.

Low to moderate tin (about 5–12% Sn) forms alpha-bronze, a mostly single-phase solid solution with improved strength and good ductility over pure copper. Higher tin contents (above roughly 12% Sn) produce harder, more wear-resistant alloys that can be two-phase and more brittle; these are often referred to as high-tin bronzes. Tin also enhances corrosion resistance, particularly against seawater and many acids, contributing to long-term durability in various environments.

Mechanical properties depend on composition and processing. Bronze typically has higher hardness and wear resistance than copper, with good fatigue strength and dimensional stability. Electrical conductivity remains below that of pure copper. Bronze is readily cast and can be forged or rolled, but high-tin compositions may be more difficult to work and heat-treat; most strength gains come from deformation processing rather than precipitation hardening.

Applications include bearings and bushings, gears, valve seats, and springs in some cases, as well as statues, sculptures, and historic coinage. Bronze is valued for its workability and weather resistance. In modern practice, bronzes cover a wide range of tin contents, with specialized alloys designed for wear resistance, low friction, or lift-critical components.