Aluminium
Aluminium is a relatively soft, ductile metal. The tensile strength of pure aluminium is approximately 49 MPa, while its alloys range from 300 to 700 MPa. Its elastic modulus is approximately 70,000 MPa, depending on the alloy. It is easily drawn and can be rolled into very thin foil. Wrought aluminium alloys can be readily machined, bent, pressed and forged even at lower temperatures. Stresses from cold working can be relieved by gentle heating (up to 250 °C). At these temperatures, duralumin can also be formed. Aluminium alloys containing 3% magnesium or silicon cast well (aluminium die castings) and can subsequently be machined. At approximately 1,2 K, pure aluminium exhibits superconducting properties. Aluminium melts at 660,4 °C and boils at 2470 °C. With a density of 2,7 g/cm3, it has the characteristics of a lightweight metal.
Because of its low density, aluminium is often used where weight reduction is essential, such as transport machinery, reducing weight and consequently fuel consumption. This applies particularly to spacecraft and aircraft. Aluminium has also become increasingly important in the automotive industry. Historically, automotive use was limited by high cost, difficulties welding aluminium parts and concerns about material fatigue and deformation. As early as the 1930s, some American companies used aluminium to reduce the weight of military amphibious vehicles. In small and medium-sized yachts, its resistance to corrosion in seawater was highly valued, as it forms a thin protective oxide layer on its surface.[19] In 2010, approximately 35% of global aluminium production was consumed by the transport equipment industry.[8]
In alloys with magnesium, silicon and other metals, aluminium's strength can be increased to levels comparable with steel. Aluminium's use for weight reduction is therefore mainly found where material cost is not a major factor. Aluminium and its alloy duralumin (an aluminium alloy with copper and molybdenum) are particularly widespread in aircraft and spacecraft manufacturing. Much of the structure of modern commercial aircraft consists of joined aluminium sheets of different strengths and alloys. In newer aircraft models (Boeing 787, Airbus A350), aluminium has been replaced by even lighter carbon-fibre synthetic materials.