MANGANESE-ALUMINUM-Manganese-boron-ganese copper-copper manganeseA hardener alloy employed for making additions of manganese to aluminum alloys. Manganese lowers the thermal conductivity of aluminum but increases its strength. Manganese up to 1.2% is used in aluminum alloys when strength and stiffness are required. One manganese-aluminum contains 25% manganese and 75 aluminum. Manganese-boron is used for deoxidizing and hardening bronzes. It contains 20 to 25% boron, with small amounts of iron, silicon, and aluminum. For deoxidizing and hardening brasses, nickel bronze, and copper-nickel alloys, manganese copper, or copper manganese, may be used. The alloys used contain 25 to 30% manganese and the balance copper. The best grades of manganese copper are made from metallic manganese and are free from iron. For nickel bronzes and nickel alloys, the manganese copper must be free of both iron and carbon, but grades containing up to 5% iron can be used for manganese bronze. Grades made from ferromanganese contain iron. Manganese copper is usually marketed in slabs with notched sections, or as shot. It has a lower melting point than metallic manganese and is thus more easily dissolved in the brass or bronze. The 30% alloy melts at about 1600°F (871°C).
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