Phosphor bronze

Phosphor bronze is an alloy of copper with 0.5–11% of tin and 0.01-0.35% phosphorus. The tin increases the corrosion resistance and strength of the alloy. The phosphorus increases the wear resistance and stiffness of the alloy.

These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain. The phosphorus reduces the viscosity of the molten alloy, which makes it easier and cleaner to cast and reduces grain boundaries between crystallites.

Phosphor bronze is used for springs, bolts, and various other items used in situations where resistance to fatigue, wear, and chemical corrosion are required (e.g., a ship's propellers in a marine environment). The alloy is also used in some dental bridges.

Grades A, C, and E – C51000, 52100, 50700 are commonly used nonferrous spring alloys. The combination of good physical properties, fair electrical conductivity, and moderate cost make phosphor bronze round, square, flat, and special-shaped wire desirable for many springs, electrical contacts, and a wide variety of wire forms where the desired properties do not require the use of more expensive beryllium copper.

Phosphor bronze (94.8% copper, 5% tin, 0.2% phosphorus) is also used in cryogenics. In this application, its combination of fair electrical conductivity and low thermal conductivity allows the making of electrical connections to devices at ultra low temperatures without adding excessive heat.

...
Wikipedia