Phosphor Bronzes are alloys containing copper, tin and phosphorous. The addition of tin increases the corrosion resistance and strength of the alloy. The phosphorous 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 also improves the fluidity of the molten metal and thereby improves the castability, and improves mechanical properties by cleaning up the grain boundaries. The phosphor bronzes have superb spring qualities, high fatigue resistance, excellent formability and solderability, and high corrosion resistance. They are primarily used for electrical products, other uses include corrosion resistant bellows, diaphragms, and spring washers. Phosphor bronze is used for springs, bolts and various other items used in situations where resistance to fatigue, wear and chemical corrosion are required.