Magnesium is a chemical element with the element symbol Mg and atomic number 12, which makes it one of the alkaline earth metals.
The most important minerals are dolomite CaMg2, magnesite MgCO3, olivine 2, enstatite MgSiO3 and kieserite MgSO4 – H2O.
Dissolved in water, it causes water hardness together with calcium.
Its modulus of elasticity is about 45 GPa. In air, magnesium is coated with an oxide layer which, unlike aluminium, is not completely opaque. Thin tapes or foils can be easily ignited. Freshly produced magnesium powder can heat up in the air until spontaneous combustion.
This forms a hardly soluble coating of magnesium hydroxide, which largely brings the reaction to a standstill. Even weak acids, such as ammonium salts, are sufficient to dissolve the hydroxide layer, as they convert the hydroxide ions to water and form soluble salts.
The most important property of magnesium alloys, which has made them more important than aluminium and its alloys, is the lightweight construction that is possible with them. However, the mechanical properties such as tensile strength and hardness are significantly lower than those of aluminium alloys. After 1930, magnesium alloys were increasingly used in aircraft construction, as the weight savings they could achieve allowed for more energy-efficient flights and higher payloads. All this led to a rapid expansion of magnesium production in Germany and after 1940 also in the USA.
Other possible uses for magnesium casting were offered in the course of technical development, partly as a result of the war, partly in a forward-looking design and at the same time optimizing the alloys. Today, magnesium alloys are not only used to save weight, but are also characterized by high damping. Camera body cast from a magnesium alloy. In the die casting process, many, even large-area, thin-walled components can be produced close to their final dimensions and without cost-intensive finishing, such as
Parts made of Mg-Al-Zn alloys are used not only in automotive engineering, but also in mechanical engineering.
Magnesium materials in medicine
Recent research promises a high development potential of magnesium materials as resorbable implant material for the human body. Magnesium materials must be protected against contact corrosion in use. This eliminated the risks and costs of an implant removal operation.
Magnesium in the form of magnesium oxide or magnesium carbonate is used in the liming of arable land and grassland to compensate for magnesium depletion by plants. Furthermore, the soil pH value is increased and the availability of further nutrients is improved.