Aluminum is a widely distributed element, which is second only to oxygen and silicon in the earth’s crust, and is the highest in metals. Pure aluminum has a low density of 2.7 g/cm3, good thermal conductivity and electrical conductivity (after Au, Ag, Cu), good ductility and high plasticity, and can be processed in various ways. Aluminum is chemically active and rapidly oxidizes in the air to form a dense, strong oxide film with good corrosion resistance. However, the strength of pure aluminum is low, and only various alloys which can be used as structural materials can be obtained by alloying.
Characteristics and nature
The outstanding features of aluminum alloys are low density and high strength. Al-Mn and Al-Mg alloys formed by adding Mn and Mg to aluminum have good corrosion resistance, good plasticity and high strength. They are called rust-proof aluminum alloys and are used to manufacture fuel tanks, containers, pipes and rivets. Wait. The strength of hard aluminum alloy is higher than that of rust-proof aluminum alloy, but the corrosion resistance is reduced. These alloys are Al-Cu-Mg and Al-Cu-Mg-Zn. The newly developed high-strength hard aluminum further increases the strength, and the density is 15% lower than that of ordinary hard aluminum, and can be extruded and used as a component such as a motorcycle skeleton and a rim. Al-Li alloys are used to make aircraft parts and advanced sports equipment that can withstand loads.
High-strength aluminum alloys are widely used in the manufacture of aircraft, ships and trucks, which increase their load capacity and speed, and are resistant to seawater erosion and magnetic avoidance.