Aluminum and Aluminum Alloys

     

    Aluminum and aluminum alloys have many outstanding attributes that lead to a wide range of applications, including good corrosion and oxidation resistance, high electrical and thermal conductivities, low density, high reflectivity, high ductility and reasonably high strength, and relatively low cost.
     
    Aluminum is a lightweight material with a density of 2.7 g/cm3 (0.1 lb/in.3). Pure aluminum and its alloys have the face-centered cubic (fcc) structure, which is stable up to its melting point at 657 °C (1215 °F). Because the fcc structure contains multiple slip planes, this crystalline structure greatly contributes to the excellent formability of aluminum alloys.
     
    Aluminum alloys display a good combination of strength and ductility. Aluminum alloys are among the easiest of all metals to form and machine. The precipitation hardening alloys can be formed in a relatively soft state and then heat treated to much higher strength levels after forming operations are complete. In addition, aluminum and its alloys are nontoxic and among the easiest to recycle of any of the structural materials.
     
    Aluminum is the most abundant metal in the Earth’s crust, but it was not until the 1800s that elemental aluminum was successfully extracted. Even the first processes developed were inefficient and extremely expensive. It is rumored that the French Emperor Napoleon III used sterling silver and gold tableware for routine dinner guests, reserving his highly prized aluminum tableware for only the most honored guests on special occasions. The situation changed in 1886 to 1888 with the nearly simultaneous development of the Hall-Héroult process for electrolytic reduction and the Bayer process for inexpensive production of alumina (Al2O3) from bauxite ore. These breakthroughs allowed the widespread production and use of aluminum and aluminum alloys. Charles Hall, the developer of the Hall-Héroult process, went on to form the Aluminum Company of America (Alcoa).